[PATCH] drm/dp_mst: correct the shifting in DP_REMOTE_I2C_READ

[Jani Nikula]

On Mon, 30 Dec 2019, Wayne Lin <Wayne.Lin at amd.com> wrote:
> [Why]
> According to DP spec, it should shift left 4 digits for NO_STOP_BIT
> in REMOTE_I2C_READ message. Not 5 digits.
>
> [How]
> Correct the shifting value of NO_STOP_BIT for DP_REMOTE_I2C_READ case in
> drm_dp_encode_sideband_req().

Which commit introduced the issue? Fixes: tag. Does it need a stable
backport? Does this fix a user visible bug?

BR,
Jani.

> Signed-off-by: Wayne Lin <Wayne.Lin at amd.com>
> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 1d1bfa49ca2b..0557e225ff67 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -393,7 +393,7 @@ drm_dp_encode_sideband_req(const struct drm_dp_sideband_msg_req_body *req,
>  			memcpy(&buf[idx], req->u.i2c_read.transactions[i].bytes, req->u.i2c_read.transactions[i].num_bytes);
>  			idx += req->u.i2c_read.transactions[i].num_bytes;
>  
> -			buf[idx] = (req->u.i2c_read.transactions[i].no_stop_bit & 0x1) << 5;
> +			buf[idx] = (req->u.i2c_read.transactions[i].no_stop_bit & 0x1) << 4;
>  			buf[idx] |= (req->u.i2c_read.transactions[i].i2c_transaction_delay & 0xf);
>  			idx++;
>  		}

-- 
Jani Nikula, Intel Open Source Graphics Center