On 5/3/2023 1:26 AM, Dmitry Baryshkov wrote:
On 03/05/2023 04:19, Jessica Zhang wrote:
Currently, word count is calculated using slice_count. This is incorrect
as downstream uses slice per packet, which is different from
slice_count.
Slice count represents the number of soft slices per interface, and its
value will not always match that of slice per packet. For example, it is
possible to have cases where there are multiple soft slices per interface
but the panel specifies only one slice per packet.
Thus, use the default value of one slice per packet and remove
slice_count
from the word count calculation.
Fixes: bc6b6ff8135c ("drm/msm/dsi: Use DSC slice(s) packet size to
compute word count")
Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/dsi/dsi_host.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c
b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 35c69dbe5f6f..b0d448ffb078 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -996,7 +996,14 @@ static void dsi_timing_setup(struct msm_dsi_host
*msm_host, bool is_bonded_dsi)
if (!msm_host->dsc)
wc = hdisplay * dsi_get_bpp(msm_host->format) / 8 + 1;
else
- wc = msm_host->dsc->slice_chunk_size *
msm_host->dsc->slice_count + 1;
+ /*
+ * When DSC is enabled, WC = slice_chunk_size *
slice_per_packet + 1.
+ * Currently, the driver only supports default value of
slice_per_packet = 1
+ *
+ * TODO: Expand drm_panel struct to hold slice_per_packet
info
+ * and adjust DSC math to account for
slice_per_packet.
slice_per_packet is not a part of the standard DSC, so I'm not sure how
that can be implemented. And definitely we should not care about the
drm_panel here. It should be either a part of drm_dsc_config, or
mipi_dsi_device.
Hi Dmitry,
IIRC slice per packet is given by the panel specs with the default value
being 1 if no value is specified, so it might be better to have it as
part of mipi_dsi_device.
Will update the TODO comment accordingly.
Thanks,
Jessica Zhang
+ */
+ wc = msm_host->dsc->slice_chunk_size + 1;
dsi_write(msm_host, REG_DSI_CMD_MDP_STREAM0_CTRL,
DSI_CMD_MDP_STREAM0_CTRL_WORD_COUNT(wc) |
--
With best wishes
Dmitry
