Hi Dan,
On Thu, 2017-04-20 at 13:24 +0300, Dan Carpenter wrote:
> We expected to end with "timeout_ms" set to zero, but it's a post-op so
> the current code ends with -1. Let's fix this by changing it to a
> pre-op.
>
> Fixes: 21898816831f ("drm/mediatek: add dsi transfer function")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Indeed without this patch the timeout error path is only ever chosen if
the busy bit happened to flip exactly in the last iteration of the loop.
Acked-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 808b995a990f..3a0b6d1057a2 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -902,7 +902,7 @@ static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
> {
> u32 timeout_ms = 500000; /* total 1s ~ 2s timeout */
>
> - while (timeout_ms--) {
> + while (--timeout_ms) {
> if (!(readl(dsi->regs + DSI_INTSTA) & DSI_BUSY))
> break;
>
>
Instead of just calling usleep_range(2, 4) up to 500000 times in this
open coded loop, this should be replaced with a single call to
readl_poll_timeout() though.
regards
Philipp
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