On Thu, Feb 17, 2022 at 04:22:25PM +0800, Hsin-Yi Wang wrote:
If the previous transfer didn't end with a command without DP_AUX_I2C_MOT, the next read trasnfer will miss the first byte. But if the command in previous transfer is requested with length 0, it's a no-op to anx7625 since it can't process this command. anx7625 requires the last command to be read command with length > 0.
It's observed that if we clear the DP_AUX_I2C_MOT in read transfer, we can still get correct data. Clear the read commands with DP_AUX_I2C_MOT bit to fix this issue.
Hi Hsin-Yi, thanks for the patch!
Reviewed-by: Xin Ji xji@analogixsemi.com
Thanks, Xin
Fixes: adca62ec370c ("drm/bridge: anx7625: Support reading edid through aux channel") Signed-off-by: Hsin-Yi Wang hsinyi@chromium.org
v1->v2: Offline discussed with Xin Ji, it's better to clear the bit on read commands only.
drivers/gpu/drm/bridge/analogix/anx7625.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c index 633618bafd75d3..2805e9bed2c2f4 100644 --- a/drivers/gpu/drm/bridge/analogix/anx7625.c +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c @@ -253,6 +253,8 @@ static int anx7625_aux_trans(struct anx7625_data *ctx, u8 op, u32 address, addrm = (address >> 8) & 0xFF; addrh = (address >> 16) & 0xFF;
if (!is_write)
op &= ~DP_AUX_I2C_MOT;cmd = DPCD_CMD(len, op);
/* Set command and length */
-- 2.35.1.265.g69c8d7142f-goog