From: Andrey Smirnov <andrew.smirnov@xxxxxxxxx> [ Upstream commit e0655feaec62d5139b6b13a7b1bbb1ab8f1c2d83 ] According to the datasheet tc358767 can transfer up to 16 bytes via its AUX channel, so the artificial limit of 8 appears to be too low. However only up to 15-bytes seem to be actually supported and trying to use 16-byte transfers results in transfers failing sporadically (with bogus status in case of I2C transfers), so limit it to 15. Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx> Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx> Cc: Andrzej Hajda <a.hajda@xxxxxxxxxxx> Cc: Laurent Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx> Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx> Cc: Andrey Gusakov <andrey.gusakov@xxxxxxxxxxxxxxxxxx> Cc: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> Cc: Cory Tusar <cory.tusar@xxxxxxxx> Cc: Chris Healy <cphealy@xxxxxxxxx> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20190619052716.16831-9-andrew.smirnov@xxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/gpu/drm/bridge/tc358767.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c index f59a51e19dab0..d515c7cebb9c4 100644 --- a/drivers/gpu/drm/bridge/tc358767.c +++ b/drivers/gpu/drm/bridge/tc358767.c @@ -293,7 +293,7 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) { struct tc_data *tc = aux_to_tc(aux); - size_t size = min_t(size_t, 8, msg->size); + size_t size = min_t(size_t, DP_AUX_MAX_PAYLOAD_BYTES - 1, msg->size); u8 request = msg->request & ~DP_AUX_I2C_MOT; u8 *buf = msg->buffer; u32 tmp = 0; -- 2.20.1
