Unverified Commit c0bbed90 authored by Hsin-Yi Wang's avatar Hsin-Yi Wang Committed by Robert Foss
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drm/bridge: Clear the DP_AUX_I2C_MOT bit passed in aux read command. 



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: adca62ec ("drm/bridge: anx7625: Support reading edid through aux channel")
Signed-off-by: default avatarHsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: default avatarXin Ji <xji@analogixsemi.com>
Signed-off-by: default avatarRobert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220217082224.1823916-1-hsinyi@chromium.org
parent 7e302637

drivers/gpu/drm/bridge/analogix/anx7625.c

+2 −0
Original line number Diff line number Diff line
@@ -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 */