| Message ID | 20220217082224.1823916-1-hsinyi@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/bridge: Clear the DP_AUX_I2C_MOT bit passed in aux read command. | expand |
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
On Thu, Feb 17, 2022 at 4:31 PM Xin Ji <xji@analogixsemi.com> wrote: > > 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 Hi Robert, Kindly ping on this fix. Thanks. > > > > 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
Applied to drm-misc-next.
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 */
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. 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(+)