[PATCH 1/2] ASoC: fsl: fsl_ssi: add ac97 fixed mode support
SSI supports "variable" and "fixed" mode of operation in AC'97 mode. Up to now, driver always configured SSI port to operate in "variable" AC'97 mode which is known to be unreliable with some CODECs, see: commit 01ca485171e3 ("ASoC: fsl_ssi: only enable proper channel slots in AC'97 mode") for more information on issues related to spurious SLOTREQ bits. But in summary, when SSI operates in AC'97 variable mode of operation, CODECs can sometimes send SLOTREQ bits for non-existent audio slots which then "stick" in SSI and completely break audio output. Contrary when operating SSI in AC'97 fixed mode, described issues were completely gone!
Thus add support for operating SSI in AC'97 Fixed Mode of operation which provides better audio reliability when compared to AC'97 Variable Mode with some CODECs.
Signed-off-by: Primoz Fiser primoz.fiser@norik.com --- sound/soc/fsl/fsl_ssi.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c index 404be27c15fe..3b89785f6de8 100644 --- a/sound/soc/fsl/fsl_ssi.c +++ b/sound/soc/fsl/fsl_ssi.c @@ -243,6 +243,7 @@ struct fsl_ssi_soc_data { * @dma_maxburst: Max number of words to transfer in one go. So far, * this is always the same as fifo_watermark. * @ac97_reg_lock: Mutex lock to serialize AC97 register access operations + * @ac97_fixed_mode: SSI in AC97 fixed mode of operation */ struct fsl_ssi { struct regmap *regs; @@ -287,6 +288,7 @@ struct fsl_ssi { u32 dma_maxburst;
struct mutex ac97_reg_lock; + bool ac97_fixed_mode; };
/* @@ -616,7 +618,12 @@ static void fsl_ssi_setup_ac97(struct fsl_ssi *ssi) regmap_write(regs, REG_SSI_SRCCR, SSI_SxCCR_WL(17) | SSI_SxCCR_DC(13));
/* Enable AC97 mode and startup the SSI */ - regmap_write(regs, REG_SSI_SACNT, SSI_SACNT_AC97EN | SSI_SACNT_FV); + if (ssi->ac97_fixed_mode) { + regmap_write(regs, REG_SSI_SACNT, SSI_SACNT_AC97EN); + regmap_write(regs, REG_SSI_SATAG, 0x9800); + } else + regmap_write(regs, REG_SSI_SACNT, + SSI_SACNT_AC97EN | SSI_SACNT_FV);
/* AC97 has to communicate with codec before starting a stream */ regmap_update_bits(regs, REG_SSI_SCR, @@ -1092,8 +1099,10 @@ static int fsl_ssi_trigger(struct snd_pcm_substream *substream, int cmd, * send valid data to slots other than normal playback slots. * * To be safe, configure SACCST right before TX starts. + * + * Above applies only when SSI operates in AC97 Variable Mode. */ - if (tx && fsl_ssi_is_ac97(ssi)) + if (tx && fsl_ssi_is_ac97(ssi) && !ssi->ac97_fixed_mode) fsl_ssi_tx_ac97_saccst_setup(ssi); fsl_ssi_config_enable(ssi, tx); break; @@ -1437,6 +1446,11 @@ static int fsl_ssi_probe_from_dt(struct fsl_ssi *ssi) ssi->synchronous = true; }
+ /* Check AC97 mode of operation */ + sprop = of_get_property(np, "fsl,ac97-mode", NULL); + if (sprop && !strcmp(sprop, "fixed")) + ssi->ac97_fixed_mode = true; + /* Select DMA or FIQ */ ssi->use_dma = !of_property_read_bool(np, "fsl,fiq-stream-filter");
Add devicetree bindings documentation for operating SSI in AC'97 variable/fixed mode of operation.
Signed-off-by: Primoz Fiser primoz.fiser@norik.com --- Documentation/devicetree/bindings/sound/fsl,ssi.txt | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/Documentation/devicetree/bindings/sound/fsl,ssi.txt b/Documentation/devicetree/bindings/sound/fsl,ssi.txt index 7e15a85cecd2..abc5abe11fb9 100644 --- a/Documentation/devicetree/bindings/sound/fsl,ssi.txt +++ b/Documentation/devicetree/bindings/sound/fsl,ssi.txt @@ -43,6 +43,11 @@ Optional properties: - fsl,mode: The operating mode for the AC97 interface only. "ac97-slave" - AC97 mode, SSI is clock slave "ac97-master" - AC97 mode, SSI is clock master +- fsl,ac97-mode: SSI AC97 mode of operation. + "variable" - AC97 Variable Mode, SLOTREQ bits determine + next receive/transmit frame + "fixed" - AC97 Fixed Mode, SSI transmits in accordance with + AC97 Frame Rate Divider bits - fsl,ssi-asynchronous: If specified, the SSI is to be programmed in asynchronous mode. In this mode, pins SRCK, STCK, SRFS, and STFS must
On Mon, Oct 5, 2020 at 8:16 AM Primoz Fiser primoz.fiser@norik.com wrote:
Add devicetree bindings documentation for operating SSI in AC'97 variable/fixed mode of operation.
Signed-off-by: Primoz Fiser primoz.fiser@norik.com
Documentation/devicetree/bindings/sound/fsl,ssi.txt | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/Documentation/devicetree/bindings/sound/fsl,ssi.txt b/Documentation/devicetree/bindings/sound/fsl,ssi.txt index 7e15a85cecd2..abc5abe11fb9 100644 --- a/Documentation/devicetree/bindings/sound/fsl,ssi.txt +++ b/Documentation/devicetree/bindings/sound/fsl,ssi.txt @@ -43,6 +43,11 @@ Optional properties:
- fsl,mode: The operating mode for the AC97 interface only. "ac97-slave" - AC97 mode, SSI is clock slave "ac97-master" - AC97 mode, SSI is clock master
+- fsl,ac97-mode: SSI AC97 mode of operation.
"variable" - AC97 Variable Mode, SLOTREQ bits determinenext receive/transmit frame"fixed" - AC97 Fixed Mode, SSI transmits in accordance withAC97 Frame Rate Divider bits
It would be good to mention what is the default mode when such property is absent.
On Mon, Oct 05, 2020 at 08:35:58AM -0300, Fabio Estevam wrote:
On Mon, Oct 5, 2020 at 8:16 AM Primoz Fiser primoz.fiser@norik.com wrote:
Add devicetree bindings documentation for operating SSI in AC'97 variable/fixed mode of operation.
Signed-off-by: Primoz Fiser primoz.fiser@norik.com
Documentation/devicetree/bindings/sound/fsl,ssi.txt | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/Documentation/devicetree/bindings/sound/fsl,ssi.txt b/Documentation/devicetree/bindings/sound/fsl,ssi.txt index 7e15a85cecd2..abc5abe11fb9 100644 --- a/Documentation/devicetree/bindings/sound/fsl,ssi.txt +++ b/Documentation/devicetree/bindings/sound/fsl,ssi.txt @@ -43,6 +43,11 @@ Optional properties:
- fsl,mode: The operating mode for the AC97 interface only. "ac97-slave" - AC97 mode, SSI is clock slave "ac97-master" - AC97 mode, SSI is clock master
+- fsl,ac97-mode: SSI AC97 mode of operation.
"variable" - AC97 Variable Mode, SLOTREQ bits determinenext receive/transmit frame"fixed" - AC97 Fixed Mode, SSI transmits in accordance withAC97 Frame Rate Divider bitsIt would be good to mention what is the default mode when such property is absent.
Then perhaps it could be boolean?
Rob
Hi,
Then perhaps it could be boolean?
Indeed, I can make it boolean.
In that case I would rename property to "fsl,ac97-fixed-mode".
Should I do that for V2?
Please advise.
BR, Primoz
On 6. 10. 20 23:52, Rob Herring wrote:
On Mon, Oct 05, 2020 at 08:35:58AM -0300, Fabio Estevam wrote:
On Mon, Oct 5, 2020 at 8:16 AM Primoz Fiser primoz.fiser@norik.com wrote:
Add devicetree bindings documentation for operating SSI in AC'97 variable/fixed mode of operation.
Signed-off-by: Primoz Fiser primoz.fiser@norik.com
Documentation/devicetree/bindings/sound/fsl,ssi.txt | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/Documentation/devicetree/bindings/sound/fsl,ssi.txt b/Documentation/devicetree/bindings/sound/fsl,ssi.txt index 7e15a85cecd2..abc5abe11fb9 100644 --- a/Documentation/devicetree/bindings/sound/fsl,ssi.txt +++ b/Documentation/devicetree/bindings/sound/fsl,ssi.txt @@ -43,6 +43,11 @@ Optional properties:
- fsl,mode: The operating mode for the AC97 interface only. "ac97-slave" - AC97 mode, SSI is clock slave "ac97-master" - AC97 mode, SSI is clock master
+- fsl,ac97-mode: SSI AC97 mode of operation.
"variable" - AC97 Variable Mode, SLOTREQ bits determinenext receive/transmit frame"fixed" - AC97 Fixed Mode, SSI transmits in accordance withAC97 Frame Rate Divider bitsIt would be good to mention what is the default mode when such property is absent.
Then perhaps it could be boolean?
Rob
Hi Primoz,
On Mon, Oct 5, 2020 at 8:16 AM Primoz Fiser primoz.fiser@norik.com wrote:
SSI supports "variable" and "fixed" mode of operation in AC'97 mode. Up to now, driver always configured SSI port to operate in "variable" AC'97 mode which is known to be unreliable with some CODECs, see: commit 01ca485171e3 ("ASoC: fsl_ssi: only enable proper channel slots in AC'97 mode") for more information on issues related to spurious SLOTREQ bits. But in summary, when SSI operates in AC'97 variable mode of operation, CODECs can sometimes send SLOTREQ bits for non-existent audio slots which then "stick" in SSI and completely break audio output. Contrary when operating SSI in AC'97 fixed mode, described issues were completely gone!
Thus add support for operating SSI in AC'97 Fixed Mode of operation which provides better audio reliability when compared to AC'97 Variable Mode with some CODECs.
Signed-off-by: Primoz Fiser primoz.fiser@norik.com
sound/soc/fsl/fsl_ssi.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c index 404be27c15fe..3b89785f6de8 100644 --- a/sound/soc/fsl/fsl_ssi.c +++ b/sound/soc/fsl/fsl_ssi.c @@ -243,6 +243,7 @@ struct fsl_ssi_soc_data {
- @dma_maxburst: Max number of words to transfer in one go. So far,
this is always the same as fifo_watermark.- @ac97_reg_lock: Mutex lock to serialize AC97 register access operations
*/
- @ac97_fixed_mode: SSI in AC97 fixed mode of operation
struct fsl_ssi { struct regmap *regs; @@ -287,6 +288,7 @@ struct fsl_ssi { u32 dma_maxburst;
struct mutex ac97_reg_lock;
bool ac97_fixed_mode;};
/* @@ -616,7 +618,12 @@ static void fsl_ssi_setup_ac97(struct fsl_ssi *ssi) regmap_write(regs, REG_SSI_SRCCR, SSI_SxCCR_WL(17) | SSI_SxCCR_DC(13));
/* Enable AC97 mode and startup the SSI */
regmap_write(regs, REG_SSI_SACNT, SSI_SACNT_AC97EN | SSI_SACNT_FV);
if (ssi->ac97_fixed_mode) {regmap_write(regs, REG_SSI_SACNT, SSI_SACNT_AC97EN);regmap_write(regs, REG_SSI_SATAG, 0x9800);} else
Should be } else { because the previous if block used curly braces.
regmap_write(regs, REG_SSI_SACNT,SSI_SACNT_AC97EN | SSI_SACNT_FV);
On Mon, Oct 05, 2020 at 01:16:43PM +0200, Primoz Fiser wrote:
bits. But in summary, when SSI operates in AC'97 variable mode of operation, CODECs can sometimes send SLOTREQ bits for non-existent audio slots which then "stick" in SSI and completely break audio output.
If this is something that happens based on the CODEC shouldn't we be doing this by quirking based on the CODEC the system has rather than requiring people set a separate DT property?
Hi Mark,
On 5. 10. 20 13:49, Mark Brown wrote:
On Mon, Oct 05, 2020 at 01:16:43PM +0200, Primoz Fiser wrote:
bits. But in summary, when SSI operates in AC'97 variable mode of operation, CODECs can sometimes send SLOTREQ bits for non-existent audio slots which then "stick" in SSI and completely break audio output.
If this is something that happens based on the CODEC shouldn't we be doing this by quirking based on the CODEC the system has rather than requiring people set a separate DT property?
To be totally honest, we are not 100% sure if this is only CODEC's fault or something else might be causing these issues.
For example, it could be some EMI/noise that causes SLOTREQ bits to flip spuriously. Or it could even be the buggy SSI itself (taking into account all the issues with channel slipping, slot filtering, AC'97 reg reading/writing, etc)?
We are just referencing commit 01ca485171e3 ("ASoC: fsl_ssi: only enable proper channel slots in AC'97 mode"), as we saw that UDOO board had the same problems. I added commit author to CC.
We were able to overcome those by programming SSI in AC'97 fixed mode which driver up to now completely ignored (it was using only AC'97 variable mode).
Additionally, we are using WM9712 codec and UDOO board is using VT1613, right? So these issues might not be CODEC related at all.
BR, Primoz
On 05.10.2020 14:59, Primoz Fiser wrote:
Hi Mark,
On 5. 10. 20 13:49, Mark Brown wrote:
On Mon, Oct 05, 2020 at 01:16:43PM +0200, Primoz Fiser wrote:
bits. But in summary, when SSI operates in AC'97 variable mode of operation, CODECs can sometimes send SLOTREQ bits for non-existent audio slots which then "stick" in SSI and completely break audio output.
If this is something that happens based on the CODEC shouldn't we be doing this by quirking based on the CODEC the system has rather than requiring people set a separate DT property?
To be totally honest, we are not 100% sure if this is only CODEC's fault or something else might be causing these issues.
For example, it could be some EMI/noise that causes SLOTREQ bits to flip spuriously. Or it could even be the buggy SSI itself (taking into account all the issues with channel slipping, slot filtering, AC'97 reg reading/writing, etc)?
We are just referencing commit 01ca485171e3 ("ASoC: fsl_ssi: only enable proper channel slots in AC'97 mode"), as we saw that UDOO board had the same problems. I added commit author to CC.
We were able to overcome those by programming SSI in AC'97 fixed mode which driver up to now completely ignored (it was using only AC'97 variable mode).
Additionally, we are using WM9712 codec and UDOO board is using VT1613, right? So these issues might not be CODEC related at all.
I remember that the AC'97 mode in SSI was riddled with bugs to a level of being barely usable.
Not only the channel slots would enable on their own, but the CODEC registers got randomly trashed from time to time (I think a register would get zeroed spontaneously).
This happened even if an external CODEC, different than the boards VT1613, was connected. So these were definitely SSI problems, not CODEC ones.
That's why probably pretty much every board other than UDOO uses SSI in the I²S mode.
Maciej
Hi Maciej,
I remember that the AC'97 mode in SSI was riddled with bugs to a level of being barely usable.
True.
After exhausting work we managed to get it stable enough to be ready for "production". One of improvements was the use of AC'97 fixed mode instead of variable mode. Other improvements to fsl_ssi by us might follow in the future, but at the moment I don't think those are ready for "mainline".
Not only the channel slots would enable on their own, but the CODEC registers got randomly trashed from time to time (I think a register would get zeroed spontaneously).
Yes, we also encountered those issues. For this we use special thread in a loop to check the state of AC'97 registers. We store known good values and check for discrepancies while audio is running. Once discrepancy is found, we immediately recover the register value with the previous good value. Downside of this approach is that audio might be down for a period of thread loop and that's why we keep it tight at 1 Hz.
BR, Primoz
On 5. 10. 20 15:51, Maciej S. Szmigiero wrote:
On 05.10.2020 14:59, Primoz Fiser wrote:
Hi Mark,
On 5. 10. 20 13:49, Mark Brown wrote:
On Mon, Oct 05, 2020 at 01:16:43PM +0200, Primoz Fiser wrote:
bits. But in summary, when SSI operates in AC'97 variable mode of operation, CODECs can sometimes send SLOTREQ bits for non-existent audio slots which then "stick" in SSI and completely break audio output.
If this is something that happens based on the CODEC shouldn't we be doing this by quirking based on the CODEC the system has rather than requiring people set a separate DT property?
To be totally honest, we are not 100% sure if this is only CODEC's fault or something else might be causing these issues.
For example, it could be some EMI/noise that causes SLOTREQ bits to flip spuriously. Or it could even be the buggy SSI itself (taking into account all the issues with channel slipping, slot filtering, AC'97 reg reading/writing, etc)?
We are just referencing commit 01ca485171e3 ("ASoC: fsl_ssi: only enable proper channel slots in AC'97 mode"), as we saw that UDOO board had the same problems. I added commit author to CC.
We were able to overcome those by programming SSI in AC'97 fixed mode which driver up to now completely ignored (it was using only AC'97 variable mode).
Additionally, we are using WM9712 codec and UDOO board is using VT1613, right? So these issues might not be CODEC related at all.
I remember that the AC'97 mode in SSI was riddled with bugs to a level of being barely usable.
Not only the channel slots would enable on their own, but the CODEC registers got randomly trashed from time to time (I think a register would get zeroed spontaneously).
This happened even if an external CODEC, different than the boards VT1613, was connected. So these were definitely SSI problems, not CODEC ones.
That's why probably pretty much every board other than UDOO uses SSI in the I²S mode.
Maciej
On Mon, Oct 05, 2020 at 02:59:53PM +0200, Primoz Fiser wrote:
On 5. 10. 20 13:49, Mark Brown wrote:
If this is something that happens based on the CODEC shouldn't we be doing this by quirking based on the CODEC the system has rather than requiring people set a separate DT property?
To be totally honest, we are not 100% sure if this is only CODEC's fault or something else might be causing these issues.
OK, the description made it sound like it was an interop issue with the CODEC but if there's concerns about there being board related issues then a property is fine.
Additionally, we are using WM9712 codec and UDOO board is using VT1613, right? So these issues might not be CODEC related at all.
ISTR people had got the WM9712 (or was it WM9713?) working with some i.MX SoCs.
participants (5)
-
Fabio Estevam -
Maciej S. Szmigiero -
Mark Brown -
Primoz Fiser -
Rob Herring