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SubjectRe: [PATCH v3 03/15] drm/bridge: tc358767: Simplify polling in tc_link_training()
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On 05.06.2019 09:04, Andrey Smirnov wrote:
> Replace explicit polling in tc_link_training() with equivalent call to
> tc_poll_timeout() for simplicity. No functional change intended (not
> including slightly altered debug output).
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> Cc: Archit Taneja <architt@codeaurora.org>
> Cc: Andrzej Hajda <a.hajda@samsung.com>
> Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Cc: Andrey Gusakov <andrey.gusakov@cogentembedded.com>
> Cc: Philipp Zabel <p.zabel@pengutronix.de>
> Cc: Cory Tusar <cory.tusar@zii.aero>
> Cc: Chris Healy <cphealy@gmail.com>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> ---
> drivers/gpu/drm/bridge/tc358767.c | 15 ++++++---------
> 1 file changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
> index 5e1e73a91696..115cffc55a96 100644
> --- a/drivers/gpu/drm/bridge/tc358767.c
> +++ b/drivers/gpu/drm/bridge/tc358767.c
> @@ -748,22 +748,19 @@ static int tc_set_video_mode(struct tc_data *tc,
>
> static int tc_wait_link_training(struct tc_data *tc)
> {
> - u32 timeout = 1000;
> u32 value;
> int ret;
>
> - do {
> - udelay(1);
> - tc_read(DP0_LTSTAT, &value);
> - } while ((!(value & LT_LOOPDONE)) && (--timeout));
> -
> - if (timeout == 0) {
> + ret = tc_poll_timeout(tc, DP0_LTSTAT, LT_LOOPDONE,
> + LT_LOOPDONE, 1, 1000);
> + if (ret) {
> dev_err(tc->dev, "Link training timeout waiting for LT_LOOPDONE!\n");
> - return -ETIMEDOUT;
> + return ret;
> }


Inconsistent coding, in previous patch you check (ret == -ETIMEDOUT) but
not here. To simplify the code you can assume that tc_poll_timeout < 0,
means timeout, in such case please adjust previous patch.


Beside this:

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

 --
Regards
Andrzej


>
> - return (value >> 8) & 0x7;
> + tc_read(DP0_LTSTAT, &value);
>
> + return (value >> 8) & 0x7;
> err:
> return ret;
> }


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