[PATCH 0/3] ASoC: qcom: check ADSP version when setting clocks
The apq8016_sbc driver currently works on APQ8016 and MSM8916 devices. It should also work on MSM8909 (and newer SoCs like MSM8917 and MSM8953 if the quinary MI2S line is added); however, newer devices with these SoCs ship with newer firmware that uses a different interface for controlling the digital codec and bit clocks, which causes the driver to fail because it cannot set LPAIF_BIT_CLK.
In order to fix this problem, modify the LPAIF_* clock implementation in the qdsp6 driver to use the newer clock API if a newer firmware version is detected. This seems to be a better solution than exposing the firmware version to other drivers like apq8016_sbc and forcing them to figure out which clock to use.
On MSM8916, a hack is currently used to control the LPAIF_DIG_CLK directly through the GCC driver, but on devices with the newer firmware, the INTERNAL_DIGITAL_CODEC_CORE clock provided by q6afe-clocks in the qdsp6 driver can be used instead. Add a fallback to make this clock work with the older firmware too, allowing one to specify it as the codec's "mclk" in the device tree:
compatible = "qcom,msm8916-wcd-digital-codec"; clocks = <&xo_board>, <&q6afecc LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE LPASS_CLK_ATTRIBUTE_COUPLE_NO>; clock-names = "ahbix", "mclk"; assigned-clocks = <&q6afecc LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE LPASS_CLK_ATTRIBUTE_COUPLE_NO>; assigned-clock-rates = <9600000>;
This works both on MSM8916 and on the newer SoCs mentioned above.
Otto Pflüger (3): ASoC: qcom: q6core: expose ADSP core firmware version ASoC: qcom: q6afe: check ADSP version when setting clocks ASoC: qcom: q6afe: remove "port already open" error
sound/soc/qcom/qdsp6/q6afe.c | 85 +++++++++++++++++++++++++++++++++-- sound/soc/qcom/qdsp6/q6core.c | 61 +++++++++++++++++++++++++ sound/soc/qcom/qdsp6/q6core.h | 9 ++++ 3 files changed, 152 insertions(+), 3 deletions(-)
base-commit: e3b18f7200f45d66f7141136c25554ac1e82009b
Add a q6core_get_adsp_version() function that returns the version of the ADSP firmware (2.6, 2.7 or 2.8), also known as the AVS version (see [1] in downstream kernel).
Some APIs differ between these versions, e.g. the AFE clock APIs.
[1]: https://github.com/msm8916-mainline/linux-downstream/blob/LA.BR.1.2.9.1_rb1....
Signed-off-by: Otto Pflüger otto.pflueger@abscue.de --- sound/soc/qcom/qdsp6/q6core.c | 61 +++++++++++++++++++++++++++++++++++ sound/soc/qcom/qdsp6/q6core.h | 9 ++++++ 2 files changed, 70 insertions(+)
diff --git a/sound/soc/qcom/qdsp6/q6core.c b/sound/soc/qcom/qdsp6/q6core.c index 49cfb32cd209..ea6232645c80 100644 --- a/sound/soc/qcom/qdsp6/q6core.c +++ b/sound/soc/qcom/qdsp6/q6core.c @@ -20,6 +20,9 @@ #define AVCS_CMDRSP_ADSP_EVENT_GET_STATE 0x0001290D #define AVCS_GET_VERSIONS 0x00012905 #define AVCS_GET_VERSIONS_RSP 0x00012906 +#define AVCS_CMDRSP_Q6_ID_2_6 0x00040000 +#define AVCS_CMDRSP_Q6_ID_2_7 0x00040001 +#define AVCS_CMDRSP_Q6_ID_2_8 0x00040002 #define AVCS_CMD_GET_FWK_VERSION 0x001292c #define AVCS_CMDRSP_GET_FWK_VERSION 0x001292d
@@ -63,6 +66,7 @@ struct q6core { bool get_state_supported; bool get_version_supported; bool is_version_requested; + enum q6core_version adsp_version; };
static struct q6core *g_core; @@ -108,6 +112,14 @@ static int q6core_callback(struct apr_device *adev, struct apr_resp_pkt *data) if (!core->fwk_version) return -ENOMEM;
+ /* + * Since GET_VERSIONS is not called when GET_FWK_VERSION + * is successful and these commands may return completely + * different versions, assume that the version is 2.8 here. + * Older versions do not support GET_FWK_VERSION and we do + * not care if the version is newer than 2.8. + */ + core->adsp_version = Q6_ADSP_VERSION_2_8; core->fwk_version_supported = true; core->resp_received = true;
@@ -115,6 +127,7 @@ static int q6core_callback(struct apr_device *adev, struct apr_resp_pkt *data) } case AVCS_GET_VERSIONS_RSP: { struct avcs_cmdrsp_get_version *v; + int i;
v = data->payload;
@@ -125,6 +138,28 @@ static int q6core_callback(struct apr_device *adev, struct apr_resp_pkt *data) if (!core->svc_version) return -ENOMEM;
+ for (i = 0; i < g_core->svc_version->num_services; i++) { + struct avcs_svc_info *info; + + info = &g_core->svc_version->svc_api_info[i]; + if (info->service_id != APR_SVC_ADSP_CORE) + continue; + + switch (info->version) { + case AVCS_CMDRSP_Q6_ID_2_6: + core->adsp_version = Q6_ADSP_VERSION_2_6; + break; + case AVCS_CMDRSP_Q6_ID_2_7: + core->adsp_version = Q6_ADSP_VERSION_2_7; + break; + case AVCS_CMDRSP_Q6_ID_2_8: + core->adsp_version = Q6_ADSP_VERSION_2_8; + break; + } + + break; + } + core->get_version_supported = true; core->resp_received = true;
@@ -293,6 +328,31 @@ int q6core_get_svc_api_info(int svc_id, struct q6core_svc_api_info *ainfo) } EXPORT_SYMBOL_GPL(q6core_get_svc_api_info);
+/** + * q6core_get_adsp_version() - Get the core version number. + * + * Return: version code or Q6_ADSP_VERSION_UNKNOWN on failure + */ +enum q6core_version q6core_get_adsp_version(void) +{ + int ret; + + if (!g_core) + return Q6_ADSP_VERSION_UNKNOWN; + + mutex_lock(&g_core->lock); + if (!g_core->is_version_requested) { + if (q6core_get_fwk_versions(g_core) == -ENOTSUPP) + q6core_get_svc_versions(g_core); + g_core->is_version_requested = true; + } + ret = g_core->adsp_version; + mutex_unlock(&g_core->lock); + + return ret; +} +EXPORT_SYMBOL_GPL(q6core_get_adsp_version); + /** * q6core_is_adsp_ready() - Get status of adsp * @@ -334,6 +394,7 @@ static int q6core_probe(struct apr_device *adev) dev_set_drvdata(&adev->dev, g_core);
mutex_init(&g_core->lock); + g_core->adsp_version = Q6_ADSP_VERSION_UNKNOWN; g_core->adev = adev; init_waitqueue_head(&g_core->wait); return 0; diff --git a/sound/soc/qcom/qdsp6/q6core.h b/sound/soc/qcom/qdsp6/q6core.h index 4105b1d730be..472e06bf8efc 100644 --- a/sound/soc/qcom/qdsp6/q6core.h +++ b/sound/soc/qcom/qdsp6/q6core.h @@ -9,7 +9,16 @@ struct q6core_svc_api_info { uint32_t api_branch_version; };
+/* Versions must be in order! */ +enum q6core_version { + Q6_ADSP_VERSION_UNKNOWN, + Q6_ADSP_VERSION_2_6, + Q6_ADSP_VERSION_2_7, + Q6_ADSP_VERSION_2_8, +}; + bool q6core_is_adsp_ready(void); +enum q6core_version q6core_get_adsp_version(void); int q6core_get_svc_api_info(int svc_id, struct q6core_svc_api_info *ainfo);
#endif /* __Q6CORE_H__ */
On Sat, Oct 14, 2023 at 07:26:22PM +0200, Otto Pflüger wrote:
for (i = 0; i < g_core->svc_version->num_services; i++) {struct avcs_svc_info *info;info = &g_core->svc_version->svc_api_info[i];if (info->service_id != APR_SVC_ADSP_CORE)continue;switch (info->version) {case AVCS_CMDRSP_Q6_ID_2_6:core->adsp_version = Q6_ADSP_VERSION_2_6;break;case AVCS_CMDRSP_Q6_ID_2_7:core->adsp_version = Q6_ADSP_VERSION_2_7;break;case AVCS_CMDRSP_Q6_ID_2_8:core->adsp_version = Q6_ADSP_VERSION_2_8;break;}
This doesn't handle unknown versions at all.
On Mon, Oct 16, 2023 at 01:47:28PM +0100, Mark Brown wrote:
On Sat, Oct 14, 2023 at 07:26:22PM +0200, Otto Pflüger wrote:
for (i = 0; i < g_core->svc_version->num_services; i++) {struct avcs_svc_info *info;info = &g_core->svc_version->svc_api_info[i];if (info->service_id != APR_SVC_ADSP_CORE)continue;switch (info->version) {case AVCS_CMDRSP_Q6_ID_2_6:core->adsp_version = Q6_ADSP_VERSION_2_6;break;case AVCS_CMDRSP_Q6_ID_2_7:core->adsp_version = Q6_ADSP_VERSION_2_7;break;case AVCS_CMDRSP_Q6_ID_2_8:core->adsp_version = Q6_ADSP_VERSION_2_8;break;}This doesn't handle unknown versions at all.
The adsp_version is initialized to Q6_ADSP_VERSION_UNKNOWN in q6core_probe, so it should stay unknown if it doesn't match any of these values. I don't see any big problems here, but I agree that some additional handling such as a warning message could be useful.
There are two APIs for setting clocks: the old one that uses AFE_PARAM_ID_INT_DIGITAL_CDC_CLK_CONFIG and AFE_PARAM_ID_LPAIF_CLK_CONFIG, and the new one which uses AFE_PARAM_ID_CLOCK_SET.
ADSP firmware version 2.6 only provides the old API, while newer firmware versions only provide the new API.
Implement LPAIF_BIT_CLK and LPAIF_DIG_CLK for both APIs so that users don't have to care about the firmware version. Also fall back to setting AFE_PARAM_ID_INT_DIGITAL_CDC_CLK_CONFIG in q6afe_set_lpass_clock when setting the new Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE clock is requested to allow specifying it in the device tree on older platforms too.
Signed-off-by: Otto Pflüger otto.pflueger@abscue.de --- sound/soc/qcom/qdsp6/q6afe.c | 81 ++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+)
diff --git a/sound/soc/qcom/qdsp6/q6afe.c b/sound/soc/qcom/qdsp6/q6afe.c index 91d39f6ad0bd..87bdf741e5f6 100644 --- a/sound/soc/qcom/qdsp6/q6afe.c +++ b/sound/soc/qcom/qdsp6/q6afe.c @@ -1111,6 +1111,32 @@ int q6afe_set_lpass_clock(struct device *dev, int clk_id, int attri, struct q6afe *afe = dev_get_drvdata(dev->parent); struct afe_clk_set cset = {0,};
+ /* + * v2 clocks specified in the device tree may not be supported by the + * firmware. If this is the digital codec core clock, fall back to the + * old method for setting it. + */ + if (q6core_get_adsp_version() < Q6_ADSP_VERSION_2_7) { + struct q6afe_port *port; + struct afe_digital_clk_cfg dcfg = {0,}; + int ret; + + if (clk_id != Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE) + return -EINVAL; + + port = q6afe_port_get_from_id(dev, PRIMARY_MI2S_RX); + if (IS_ERR(port)) + return PTR_ERR(port); + + dcfg.i2s_cfg_minor_version = AFE_API_VERSION_I2S_CONFIG; + dcfg.clk_val = freq; + dcfg.clk_root = 5; + ret = q6afe_set_digital_codec_core_clock(port, &dcfg); + + q6afe_port_put(port); + return ret; + } + cset.clk_set_minor_version = AFE_API_VERSION_CLOCK_SET; cset.clk_id = clk_id; cset.clk_freq_in_hz = freq; @@ -1124,6 +1150,41 @@ int q6afe_set_lpass_clock(struct device *dev, int clk_id, int attri, } EXPORT_SYMBOL_GPL(q6afe_set_lpass_clock);
+static int q6afe_get_v2_bit_clk_id(struct q6afe_port *port) +{ + switch (port->id) { + case AFE_PORT_ID_PRIMARY_MI2S_RX: + case AFE_PORT_ID_PRIMARY_MI2S_TX: + return Q6AFE_LPASS_CLK_ID_PRI_MI2S_IBIT; + case AFE_PORT_ID_SECONDARY_MI2S_RX: + case AFE_PORT_ID_SECONDARY_MI2S_TX: + return Q6AFE_LPASS_CLK_ID_SEC_MI2S_IBIT; + case AFE_PORT_ID_TERTIARY_MI2S_RX: + case AFE_PORT_ID_TERTIARY_MI2S_TX: + return Q6AFE_LPASS_CLK_ID_TER_MI2S_IBIT; + case AFE_PORT_ID_QUATERNARY_MI2S_RX: + case AFE_PORT_ID_QUATERNARY_MI2S_TX: + return Q6AFE_LPASS_CLK_ID_TER_MI2S_IBIT; + case AFE_PORT_ID_QUINARY_MI2S_RX: + case AFE_PORT_ID_QUINARY_MI2S_TX: + return Q6AFE_LPASS_CLK_ID_QUI_MI2S_IBIT; + + case AFE_PORT_ID_PRIMARY_TDM_RX ... AFE_PORT_ID_PRIMARY_TDM_TX_7: + return Q6AFE_LPASS_CLK_ID_PRI_TDM_IBIT; + case AFE_PORT_ID_SECONDARY_TDM_RX ... AFE_PORT_ID_SECONDARY_TDM_TX_7: + return Q6AFE_LPASS_CLK_ID_SEC_TDM_IBIT; + case AFE_PORT_ID_TERTIARY_TDM_RX ... AFE_PORT_ID_TERTIARY_TDM_TX_7: + return Q6AFE_LPASS_CLK_ID_TER_TDM_IBIT; + case AFE_PORT_ID_QUATERNARY_TDM_RX ... AFE_PORT_ID_QUATERNARY_TDM_TX_7: + return Q6AFE_LPASS_CLK_ID_QUAD_TDM_IBIT; + case AFE_PORT_ID_QUINARY_TDM_RX ... AFE_PORT_ID_QUINARY_TDM_TX_7: + return Q6AFE_LPASS_CLK_ID_QUIN_TDM_IBIT; + + default: + return -EINVAL; + } +} + int q6afe_port_set_sysclk(struct q6afe_port *port, int clk_id, int clk_src, int clk_root, unsigned int freq, int dir) @@ -1133,6 +1194,26 @@ int q6afe_port_set_sysclk(struct q6afe_port *port, int clk_id, struct afe_digital_clk_cfg dcfg = {0,}; int ret;
+ if (q6core_get_adsp_version() >= Q6_ADSP_VERSION_2_7) { + /* Always use the new clock API on newer platforms. */ + switch (clk_id) { + case LPAIF_DIG_CLK: + clk_src = Q6AFE_LPASS_CLK_ATTRIBUTE_COUPLE_NO; + clk_root = Q6AFE_LPASS_CLK_ROOT_DEFAULT; + clk_id = Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE; + break; + case LPAIF_BIT_CLK: + clk_src = Q6AFE_LPASS_CLK_ATTRIBUTE_COUPLE_NO; + clk_root = Q6AFE_LPASS_CLK_ROOT_DEFAULT; + clk_id = q6afe_get_v2_bit_clk_id(port); + if (clk_id < 0) + return clk_id; + break; + default: + break; + } + } + switch (clk_id) { case LPAIF_DIG_CLK: dcfg.i2s_cfg_minor_version = AFE_API_VERSION_I2S_CONFIG;
Thanks Otto for the patch, some comments below
On 14/10/2023 18:26, Otto Pflüger wrote:
There are two APIs for setting clocks: the old one that uses AFE_PARAM_ID_INT_DIGITAL_CDC_CLK_CONFIG and AFE_PARAM_ID_LPAIF_CLK_CONFIG, and the new one which uses AFE_PARAM_ID_CLOCK_SET.
ADSP firmware version 2.6 only provides the old API, while newer firmware versions only provide the new API.
Implement LPAIF_BIT_CLK and LPAIF_DIG_CLK for both APIs so that users don't have to care about the firmware version. Also fall back to setting AFE_PARAM_ID_INT_DIGITAL_CDC_CLK_CONFIG in q6afe_set_lpass_clock when setting the new Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE clock is requested to allow specifying it in the device tree on older platforms too.
Signed-off-by: Otto Pflüger otto.pflueger@abscue.de
sound/soc/qcom/qdsp6/q6afe.c | 81 ++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+)
diff --git a/sound/soc/qcom/qdsp6/q6afe.c b/sound/soc/qcom/qdsp6/q6afe.c index 91d39f6ad0bd..87bdf741e5f6 100644 --- a/sound/soc/qcom/qdsp6/q6afe.c +++ b/sound/soc/qcom/qdsp6/q6afe.c @@ -1111,6 +1111,32 @@ int q6afe_set_lpass_clock(struct device *dev, int clk_id, int attri, struct q6afe *afe = dev_get_drvdata(dev->parent); struct afe_clk_set cset = {0,};
- /*
* v2 clocks specified in the device tree may not be supported by the* firmware. If this is the digital codec core clock, fall back to the* old method for setting it.*/- if (q6core_get_adsp_version() < Q6_ADSP_VERSION_2_7) {
struct q6afe_port *port;struct afe_digital_clk_cfg dcfg = {0,};int ret;if (clk_id != Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE)return -EINVAL;
<---
port = q6afe_port_get_from_id(dev, PRIMARY_MI2S_RX);if (IS_ERR(port))return PTR_ERR(port);dcfg.i2s_cfg_minor_version = AFE_API_VERSION_I2S_CONFIG;dcfg.clk_val = freq;dcfg.clk_root = 5;ret = q6afe_set_digital_codec_core_clock(port, &dcfg);q6afe_port_put(port);
--->
Could you pl explain what are we doing in this snippet?
Isn't this what is exactly done in q6afe_mi2s_set_sysclk(LPAIF_DIG_CLK...)
return ret;- }
- cset.clk_set_minor_version = AFE_API_VERSION_CLOCK_SET; cset.clk_id = clk_id; cset.clk_freq_in_hz = freq;
@@ -1124,6 +1150,41 @@ int q6afe_set_lpass_clock(struct device *dev, int clk_id, int attri, } EXPORT_SYMBOL_GPL(q6afe_set_lpass_clock);
...
int q6afe_port_set_sysclk(struct q6afe_port *port, int clk_id, int clk_src, int clk_root, unsigned int freq, int dir) @@ -1133,6 +1194,26 @@ int q6afe_port_set_sysclk(struct q6afe_port *port, int clk_id, struct afe_digital_clk_cfg dcfg = {0,}; int ret;
- if (q6core_get_adsp_version() >= Q6_ADSP_VERSION_2_7) {
/* Always use the new clock API on newer platforms. */switch (clk_id) {case LPAIF_DIG_CLK:clk_src = Q6AFE_LPASS_CLK_ATTRIBUTE_COUPLE_NO;clk_root = Q6AFE_LPASS_CLK_ROOT_DEFAULT;clk_id = Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE;break;case LPAIF_BIT_CLK:clk_src = Q6AFE_LPASS_CLK_ATTRIBUTE_COUPLE_NO;clk_root = Q6AFE_LPASS_CLK_ROOT_DEFAULT;clk_id = q6afe_get_v2_bit_clk_id(port);if (clk_id < 0)return clk_id;break;default:break;}- }
This should be probably done in machine driver or q6afe-dai, not in q6afe.
- switch (clk_id) { case LPAIF_DIG_CLK: dcfg.i2s_cfg_minor_version = AFE_API_VERSION_I2S_CONFIG;
[...]
<---
port = q6afe_port_get_from_id(dev, PRIMARY_MI2S_RX);if (IS_ERR(port))return PTR_ERR(port);dcfg.i2s_cfg_minor_version = AFE_API_VERSION_I2S_CONFIG;dcfg.clk_val = freq;dcfg.clk_root = 5;ret = q6afe_set_digital_codec_core_clock(port, &dcfg);q6afe_port_put(port);--->
Could you pl explain what are we doing in this snippet?
Isn't this what is exactly done in q6afe_mi2s_set_sysclk(LPAIF_DIG_CLK...)
Yes, this is the same, except that q6afe_mi2s_set_sysclk is in q6afe-dai.c and relies on being part of the DAI, while this is called from q6afe-clocks.c in a context which doesn't necessarily require a DAI to be present, e.g. if q6afe-clocks is used as a simple clock controller without any DAIs defined in the device tree.
Setting the digital codec clock always requires a port, but it isn't relevant which port is used here because there is usually only one codec clock.
return ret;- }
- cset.clk_set_minor_version = AFE_API_VERSION_CLOCK_SET; cset.clk_id = clk_id; cset.clk_freq_in_hz = freq;
@@ -1124,6 +1150,41 @@ int q6afe_set_lpass_clock(struct device *dev, int clk_id, int attri, } EXPORT_SYMBOL_GPL(q6afe_set_lpass_clock);
...
int q6afe_port_set_sysclk(struct q6afe_port *port, int clk_id, int clk_src, int clk_root, unsigned int freq, int dir) @@ -1133,6 +1194,26 @@ int q6afe_port_set_sysclk(struct q6afe_port *port, int clk_id, struct afe_digital_clk_cfg dcfg = {0,}; int ret;
- if (q6core_get_adsp_version() >= Q6_ADSP_VERSION_2_7) {
/* Always use the new clock API on newer platforms. */switch (clk_id) {case LPAIF_DIG_CLK:clk_src = Q6AFE_LPASS_CLK_ATTRIBUTE_COUPLE_NO;clk_root = Q6AFE_LPASS_CLK_ROOT_DEFAULT;clk_id = Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE;break;case LPAIF_BIT_CLK:clk_src = Q6AFE_LPASS_CLK_ATTRIBUTE_COUPLE_NO;clk_root = Q6AFE_LPASS_CLK_ROOT_DEFAULT;clk_id = q6afe_get_v2_bit_clk_id(port);if (clk_id < 0)return clk_id;break;default:break;}- }
This should be probably done in machine driver or q6afe-dai, not in q6afe.
I'll put it in q6afe-dai since this fits nicely into the switch statement in q6afe_mi2s_set_sysclk.
As stated in the cover letter, I don't think adding this to the machine driver is the best option. The LPAIF_* clocks look simple and generic enough to be usable by different drivers, and making those drivers care about different clock versions in the firmware doesn't seem right.
- switch (clk_id) { case LPAIF_DIG_CLK: dcfg.i2s_cfg_minor_version = AFE_API_VERSION_I2S_CONFIG;
The clock fallback for older firmware versions now represents a use case for having multiple references to a port. Stop logging an error when a port is requested more than once because this does not indicate a problem anymore and causes unnecessary spam in dmesg.
Signed-off-by: Otto Pflüger otto.pflueger@abscue.de --- sound/soc/qcom/qdsp6/q6afe.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/sound/soc/qcom/qdsp6/q6afe.c b/sound/soc/qcom/qdsp6/q6afe.c index 87bdf741e5f6..d60c7b48e118 100644 --- a/sound/soc/qcom/qdsp6/q6afe.c +++ b/sound/soc/qcom/qdsp6/q6afe.c @@ -1647,10 +1647,8 @@ struct q6afe_port *q6afe_port_get_from_id(struct device *dev, int id)
/* if port is multiple times bind/unbind before callback finishes */ port = q6afe_find_port(afe, id); - if (port) { - dev_err(dev, "AFE Port already open\n"); + if (port) return port; - }
port_id = port_maps[id].port_id;
participants (3)
-
Mark Brown -
Otto Pflüger -
Srinivas Kandagatla