From 4c0a9b62b3e36bc5b06c1a796e5d4d938d9c556a Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Fri, 6 Mar 2020 18:49:21 -0500 Subject: [PATCH] drm/dp_mst: Make drm_dp_mst_dpcd_write() consistent with drm_dp_dpcd_write() Noticed this while having some problems with hubs sometimes not being detected on the first plug. Every single dpcd read or write function returns the number of bytes transferred on success or a negative error code, except apparently for drm_dp_mst_dpcd_write() - which returns 0 on success. There's not really any good reason for this difference that I can tell, and having the two functions give differing behavior means that drm_dp_dpcd_write() will end up returning 0 on success for MST devices, but the number of bytes transferred for everything else. So, fix that and update the kernel doc. Signed-off-by: Lyude Paul Fixes: 2f221a5efed4 ("drm/dp_mst: Add MST support to DP DPCD R/W functions") Cc: Hans de Goede Cc: Mikita Lipski Cc: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20200306234923.547873-2-lyude@redhat.com Reviewed-by: Alex Deucher --- drivers/gpu/drm/drm_dp_mst_topology.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 61e7beada8323..6485ecaddbcb2 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2063,7 +2063,7 @@ ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux, * sideband messaging as drm_dp_dpcd_write() does for local * devices via actual AUX CH. * - * Return: 0 on success, negative error code on failure. + * Return: number of bytes written on success, negative error code on failure. */ ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux, unsigned int offset, void *buffer, size_t size) @@ -3428,12 +3428,9 @@ static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr, drm_dp_queue_down_tx(mgr, txmsg); ret = drm_dp_mst_wait_tx_reply(mstb, txmsg); - if (ret > 0) { - if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) - ret = -EIO; - else - ret = 0; - } + if (ret > 0 && txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) + ret = -EIO; + kfree(txmsg); fail_put: drm_dp_mst_topology_put_mstb(mstb); -- 2.30.2