On Fri, 24 Mar 2017 18:40:32 +0100,
jeeja.kp@xxxxxxxxx wrote:
>
> From: Hardik T Shah <hardik.t.shah@xxxxxxxxx>
>
> As per hardware recommendation, for every capture stream completion
> following operations need to be done in order to reflect the actual
> data that is received in position buffer.
>
> 1. Wait for 20us before reading the DMA position in buffer once the
> interrupt is generated for stream completion.
> 2. Read any of the register to flush the DMA position value. This is
> dummy read operation.
Are these workarounds needed for the legacy driver?
If yes, which chips require it?
thanks,
Takashi
>
> Signed-off-by: Dharageswari R <dharageswari.r@xxxxxxxxx>
> Signed-off-by: Hardik T Shah <hardik.t.shah@xxxxxxxxx>
> Signed-off-by: Jeeja KP <jeeja.kp@xxxxxxxxx>
> ---
> sound/soc/intel/skylake/skl-pcm.c | 23 +++++++++++++++++++++--
> 1 file changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/intel/skylake/skl-pcm.c b/sound/soc/intel/skylake/skl-pcm.c
> index ef440d8..1823197 100644
> --- a/sound/soc/intel/skylake/skl-pcm.c
> +++ b/sound/soc/intel/skylake/skl-pcm.c
> @@ -21,6 +21,7 @@
>
> #include <linux/pci.h>
> #include <linux/pm_runtime.h>
> +#include <linux/delay.h>
> #include <sound/pcm_params.h>
> #include <sound/soc.h>
> #include "skl.h"
> @@ -1063,13 +1064,31 @@ static snd_pcm_uframes_t skl_platform_pcm_pointer
> * HAD space reflects the actual data that is transferred.
> * Use the position buffer for capture, as DPIB write gets
> * completed earlier than the actual data written to the DDR.
> + *
> + * For capture stream following workaround is required to fix the
> + * incorrect position reporting.
> + *
> + * 1. Wait for 20us before reading the DMA position in buffer once
> + * the interrupt is generated for stream completion as update happens
> + * on the HDA frame boundary i.e. 20.833uSec.
> + * 2. Read DPIB register to flush the DMA position value. This dummy
> + * read is required to flush DMA position value.
> + * 3. Read the DMA Position-in-Buffer. This value now will be equal to
> + * or greater than period boundary.
> */
> - if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
> +
> + if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
> pos = readl(ebus->bus.remap_addr + AZX_REG_VS_SDXDPIB_XBASE +
> (AZX_REG_VS_SDXDPIB_XINTERVAL *
> hdac_stream(hstream)->index));
> - else
> + } else {
> + udelay(20);
> + readl(ebus->bus.remap_addr +
> + AZX_REG_VS_SDXDPIB_XBASE +
> + (AZX_REG_VS_SDXDPIB_XINTERVAL *
> + hdac_stream(hstream)->index));
> pos = snd_hdac_stream_get_pos_posbuf(hdac_stream(hstream));
> + }
>
> if (pos >= hdac_stream(hstream)->bufsize)
> pos = 0;
> --
> 2.5.0
>
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@xxxxxxxxxxxxxxxx
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
