[PATCH] drm/mediatek: dsi: fix error codes in mtk_dsi_host_transfer()

[PATCH] drm/mediatek: dsi: fix error codes in mtk_dsi_host_transfer()

[Dan Carpenter]

There is a type bug because the return statement:

	return ret < 0 ? ret : recv_cnt;

will not return negatives on 64bit systems.  The problem is that the
function returns ssize_t types, while "ret" is int and "recv_cnt" is a
u32.  The negative values are type promoted to u32 and returned as
positive values instead of negative error codes.

Fixes: 81cc7e51c4f1 ("drm/mediatek: Allow commands to be sent during video mode")
Signed-off-by: Dan Carpenter <error27@gmail.com>
---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 7d5250351193..8e99981ca0e1 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -1016,12 +1016,12 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
 				     const struct mipi_dsi_msg *msg)
 {
 	struct mtk_dsi *dsi = host_to_dsi(host);
-	u32 recv_cnt, i;
+	ssize_t recv_cnt;
 	u8 read_data[16];
 	void *src_addr;
 	u8 irq_flag = CMD_DONE_INT_FLAG;
 	u32 dsi_mode;
-	int ret;
+	int ret, i;
 
 	dsi_mode = readl(dsi->regs + DSI_MODE_CTRL);
 	if (dsi_mode & MODE) {
@@ -1070,7 +1070,7 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
 	if (recv_cnt)
 		memcpy(msg->rx_buf, src_addr, recv_cnt);
 
-	DRM_INFO("dsi get %d byte data from the panel address(0x%x)\n",
+	DRM_INFO("dsi get %zd byte data from the panel address(0x%x)\n",
 		 recv_cnt, *((u8 *)(msg->tx_buf)));
 
 restore_dsi_mode:
-- 
2.39.1

Re: [PATCH] drm/mediatek: dsi: fix error codes in mtk_dsi_host_transfer()

[Mattijs Korpershoek]

Dear Dan,

Thank you for your patch.

On lun., févr. 27, 2023 at 13:08, Dan Carpenter <error27@gmail.com> wrote:

> There is a type bug because the return statement:
>
> 	return ret < 0 ? ret : recv_cnt;
>
> will not return negatives on 64bit systems.  The problem is that the
> function returns ssize_t types, while "ret" is int and "recv_cnt" is a
> u32.  The negative values are type promoted to u32 and returned as
> positive values instead of negative error codes.
>
> Fixes: 81cc7e51c4f1 ("drm/mediatek: Allow commands to be sent during video mode")
> Signed-off-by: Dan Carpenter <error27@gmail.com>

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 7d5250351193..8e99981ca0e1 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -1016,12 +1016,12 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>  				     const struct mipi_dsi_msg *msg)
>  {
>  	struct mtk_dsi *dsi = host_to_dsi(host);
> -	u32 recv_cnt, i;
> +	ssize_t recv_cnt;
>  	u8 read_data[16];
>  	void *src_addr;
>  	u8 irq_flag = CMD_DONE_INT_FLAG;
>  	u32 dsi_mode;
> -	int ret;
> +	int ret, i;
>  
>  	dsi_mode = readl(dsi->regs + DSI_MODE_CTRL);
>  	if (dsi_mode & MODE) {
> @@ -1070,7 +1070,7 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>  	if (recv_cnt)
>  		memcpy(msg->rx_buf, src_addr, recv_cnt);
>  
> -	DRM_INFO("dsi get %d byte data from the panel address(0x%x)\n",
> +	DRM_INFO("dsi get %zd byte data from the panel address(0x%x)\n",
>  		 recv_cnt, *((u8 *)(msg->tx_buf)));
>  
>  restore_dsi_mode:
> -- 
> 2.39.1

Re: [PATCH] drm/mediatek: dsi: fix error codes in mtk_dsi_host_transfer()

[AngeloGioacchino Del Regno]

Il 27/02/23 11:08, Dan Carpenter ha scritto:
> There is a type bug because the return statement:
> 
> 	return ret < 0 ? ret : recv_cnt;
> 
> will not return negatives on 64bit systems.  The problem is that the
> function returns ssize_t types, while "ret" is int and "recv_cnt" is a
> u32.  The negative values are type promoted to u32 and returned as
> positive values instead of negative error codes.
> 
> Fixes: 81cc7e51c4f1 ("drm/mediatek: Allow commands to be sent during video mode")
> Signed-off-by: Dan Carpenter <error27@gmail.com>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>