Skip to content
  1. Nov 14, 2017
  3. Nov 08, 2017
  5. Nov 02, 2017
  7. Oct 31, 2017
  9. Oct 24, 2017
  11. Oct 23, 2017
  13. Oct 20, 2017
    • Alexander Kochetkov's avatar
      dmaengine: pl330: fix descriptor allocation fail · e5887103
      Alexander Kochetkov authored 
      

If two concurrent threads call pl330_get_desc() when DMAC descriptor
pool is empty it is possible that allocation for one of threads will fail
with message:

kernel: dma-pl330 20078000.dma-controller: pl330_get_desc:2469 ALERT!

Here how that can happen. Thread A calls pl330_get_desc() to get
descriptor. If DMAC descriptor pool is empty pl330_get_desc() allocates
new descriptor on shared pool using add_desc() and then get newly
allocated descriptor using pluck_desc(). At the same time thread B calls
pluck_desc() and take newly allocated descriptor. In that case descriptor
allocation for thread A will fail.

Using on-stack pool for new descriptor allow avoid the issue described.
The patch modify pl330_get_desc() to use on-stack pool for allocation
new descriptors.

Signed-off-by: default avatarAlexander Kochetkov <al.kochet@gmail.com>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
      e5887103
    • Hiroyuki Yokoyama's avatar
      dmaengine: rcar-dmac: use TCRB instead of TCR for residue · 847449f2
      Hiroyuki Yokoyama authored 
      SYS/RT/Audio DMAC includes independent data buffers for reading
and writing. Therefore, the read transfer counter and write transfer
counter have different values.
TCR indicates read counter, and TCRB indicates write counter.
The relationship is like below.

        TCR       TCRB
[SOURCE] -> [DMAC] -> [SINK]

In the MEM_TO_DEV direction, what really matters is how much data has
been written to the device. If the DMA is interrupted between read and
write, then, the data doesn't end up in the destination, so shouldn't
be counted. TCRB is thus the register we should use in this cases.

In the DEV_TO_MEM direction, the situation is more complex. Both the
read and write side are important. What matters from a data consumer
point of view is how much data has been written to memory.
On the other hand, if the transfer is interrupted between read and
write, we'll end up losing data. It can also be important to report.

In the MEM_TO_MEM direction, what matters is of course how much data
has been written to memory from data consumer point of view.
Here, because read and write have independent data buffers, it will
take a while for TCR and TCRB to become equal. Thus we should check
TCRB in this case, too.

Thus, all cases we should check TCRB instead of TCR.

Without this patch, Sound Capture has noise after PluseAudio support
(= 07b7acb5

 ("ASoC: rsnd: update pointer more accurate")), because
the recorder will use wrong residue counter which indicates transferred
from sound device, but in reality the data was not yet put to memory
and recorder will record it.

Signed-off-by: default avatarHiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
[Kuninori: added detail information in log]
Signed-off-by: default avatarKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
      847449f2
  15. Oct 16, 2017