[alsa-devel] Accessing alsa user space buffer from external io type plugin
Hello,
I am debugging an userspace external io type plugin, written for an ARM based board where the plugin interacts with DSP directly using shared memory.
Every time I have to send period_size data to the DSP, I have my own write/read methods to do so.
I am having a problem accessing the alsa ring buffer, my transfer function looks like following.
static char * temp; static snd_pcm_sframes_t alsa_transfer(snd_pcm_ioplug_t *io, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size) {
......
temp = malloc(period_size); memcpy(temp, unsigned char *)areas->addr + (areas->first + areas->step * offset) / 8, period_size); write_to_dsp(temp, period_size); ....... }
All the book keeping is done properly, the first chunk of data is sent properly to DSP and pointer() returns correct value, next time when transfer is called, the memcpy gives segfault. ALSA buffer is an interleaved buffer and I am not using mmap mode. Any idea what might be wrong?
When I do something like this: memcpy(temp, "test data test data", period_size); the data is sent properly to DSP, but alsa buffer data is not getting accessed properly.
On Mon, Mar 24, 2008 at 4:13 PM, sandeep lahane sandeep.lahane@gmail.com wrote:
Hello,
I am debugging an userspace external io type plugin, written for an ARM based board where the plugin interacts with DSP directly using shared memory.
Every time I have to send period_size data to the DSP, I have my own write/read methods to do so.
I am having a problem accessing the alsa ring buffer, my transfer function looks like following.
static char * temp; static snd_pcm_sframes_t alsa_transfer(snd_pcm_ioplug_t *io, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size) {
...... temp = malloc(period_size); memcpy(temp, unsigned char *)areas->addr + (areas->first +areas->step * offset) / 8, period_size); write_to_dsp(temp, period_size); ....... }
All the book keeping is done properly, the first chunk of data is sent properly to DSP and pointer() returns correct value, next time when transfer is called, the memcpy gives segfault. ALSA buffer is an interleaved buffer and I am not using mmap mode. Any idea what might be wrong?
When I do something like this: memcpy(temp, "test data test data", period_size); the data is sent properly to DSP, but alsa buffer data is not getting accessed properly.
Regards, Sandeep. _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
temp is actually malloc'd in hw_params and freed properly, so please ignore the details like whether it is freed etc or not.
On Mon, Mar 24, 2008 at 4:17 PM, Pharaoh . pharaoh137@gmail.com wrote:
On Mon, Mar 24, 2008 at 4:13 PM, sandeep lahane sandeep.lahane@gmail.com wrote:
Hello,
I am debugging an userspace external io type plugin, written for an ARM based board where the plugin interacts with DSP directly using shared memory.
Every time I have to send period_size data to the DSP, I have my own write/read methods to do so.
I am having a problem accessing the alsa ring buffer, my transfer function looks like following.
static char * temp; static snd_pcm_sframes_t alsa_transfer(snd_pcm_ioplug_t *io, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size) {
...... temp = malloc(period_size); memcpy(temp, unsigned char *)areas->addr + (areas->first +areas->step * offset) / 8, period_size); write_to_dsp(temp, period_size); ....... }
All the book keeping is done properly, the first chunk of data is sent properly to DSP and pointer() returns correct value, next time when transfer is called, the memcpy gives segfault. ALSA buffer is an interleaved buffer and I am not using mmap mode. Any idea what might be wrong?
When I do something like this: memcpy(temp, "test data test data", period_size); the data is sent properly to DSP, but alsa buffer data is not getting accessed properly.
Regards, Sandeep. _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
temp is actually malloc'd in hw_params and freed properly, so please ignore the details like whether it is freed etc or not.
If I change the optimization level to O3, all the values passed from alsa upper layer to my plugin are wrong. The reason I tried changing optimization levels is that I have faced problems with ARM gcc 4.1.1. before when compiled at O levels more than zero. Are there any known problems with ARM gcc 4.1.1 and alsa-lib 1.0.13?
On Mon, Mar 24, 2008 at 6:41 PM, sandeep lahane sandeep.lahane@gmail.com wrote:
On Mon, Mar 24, 2008 at 4:17 PM, Pharaoh . pharaoh137@gmail.com wrote:
On Mon, Mar 24, 2008 at 4:13 PM, sandeep lahane < sandeep.lahane@gmail.com> wrote:
Hello,
I am debugging an userspace external io type plugin, written for an ARM based board where the plugin interacts with DSP directly using shared memory.
Every time I have to send period_size data to the DSP, I have my own write/read methods to do so.
I am having a problem accessing the alsa ring buffer, my transfer function looks like following.
static char * temp; static snd_pcm_sframes_t alsa_transfer(snd_pcm_ioplug_t *io, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size) {
...... temp = malloc(period_size); memcpy(temp, unsigned char *)areas->addr + (areas->first +areas->step * offset) / 8, period_size); write_to_dsp(temp, period_size); ....... }
All the book keeping is done properly, the first chunk of data is sent properly to DSP and pointer() returns correct value, next time when transfer is called, the memcpy gives segfault. ALSA buffer is an interleaved buffer and I am not using mmap mode. Any idea what might be wrong?
When I do something like this: memcpy(temp, "test data test data", period_size); the data is sent properly to DSP, but alsa buffer data is not getting accessed properly.
Regards, Sandeep. _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
temp is actually malloc'd in hw_params and freed properly, so please ignore the details like whether it is freed etc or not.
If I change the optimization level to O3, all the values passed from alsa upper layer to my plugin are wrong. The reason I tried changing optimization levels is that I have faced problems with ARM gcc 4.1.1. before when compiled at O levels more than zero. Are there any known problems with ARM gcc 4.1.1 and alsa-lib 1.0.13?
--
Regards, Sandeep.
Following values are wrong in transfer callback, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size
On Mon, Mar 24, 2008 at 6:43 PM, sandeep lahane sandeep.lahane@gmail.com wrote:
On Mon, Mar 24, 2008 at 6:41 PM, sandeep lahane sandeep.lahane@gmail.com wrote:
On Mon, Mar 24, 2008 at 4:17 PM, Pharaoh . pharaoh137@gmail.com wrote:
On Mon, Mar 24, 2008 at 4:13 PM, sandeep lahane < sandeep.lahane@gmail.com> wrote:
Hello,
I am debugging an userspace external io type plugin, written for an ARM based board where the plugin interacts with DSP directly using shared memory.
Every time I have to send period_size data to the DSP, I have my own write/read methods to do so.
I am having a problem accessing the alsa ring buffer, my transfer function looks like following.
static char * temp; static snd_pcm_sframes_t alsa_transfer(snd_pcm_ioplug_t *io, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size) {
...... temp = malloc(period_size); memcpy(temp, unsigned char *)areas->addr + (areas->first +areas->step * offset) / 8, period_size); write_to_dsp(temp, period_size); ....... }
All the book keeping is done properly, the first chunk of data is sent properly to DSP and pointer() returns correct value, next time when transfer is called, the memcpy gives segfault. ALSA buffer is an interleaved buffer and I am not using mmap mode. Any idea what might be wrong?
When I do something like this: memcpy(temp, "test data test data", period_size); the data is sent properly to DSP, but alsa buffer data is not getting accessed properly.
Regards, Sandeep. _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
temp is actually malloc'd in hw_params and freed properly, so please ignore the details like whether it is freed etc or not.
If I change the optimization level to O3, all the values passed from alsa upper layer to my plugin are wrong. The reason I tried changing optimization levels is that I have faced problems with ARM gcc 4.1.1. before when compiled at O levels more than zero. Are there any known problems with ARM gcc 4.1.1 and alsa-lib 1.0.13?
--
Regards, Sandeep.
Following values are wrong in transfer callback, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size
--
Regards, Sandeep.
Sorted out. Return value of transfer was wrong. Thanks.
participants (2)
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Pharaoh . -
sandeep lahane