linux-kernel - Re: [PATCH v11 17/19] drm: bridge: analogix/dp: expand the look time for waiting AUX CH reply

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Date:	Tue, 22 Dec 2015 21:26:52 +0900
From:	"Jingoo Han" <jingoohan1@...il.com>
To:	"'Yakir Yang'" <ykk@...k-chips.com>,
	"'Inki Dae'" <inki.dae@...sung.com>,
	"'Mark Yao'" <mark.yao@...k-chips.com>,
	"'Heiko Stuebner'" <heiko@...ech.de>
Cc:	"'Thierry Reding'" <treding@...dia.com>,
	"'Krzysztof Kozlowski'" <k.kozlowski@...sung.com>,
	"'Rob Herring'" <robh+dt@...nel.org>,
	"'Russell King'" <linux@....linux.org.uk>,
	<emil.l.velikov@...il.com>,
	"'Gustavo Padovan'" <gustavo.padovan@...labora.co.uk>,
	"'Kishon Vijay Abraham I'" <kishon@...com>,
	<javier@....samsung.com>, "'Andy Yan'" <andy.yan@...k-chips.com>,
	<dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-samsung-soc@...r.kernel.org>,
	<linux-rockchip@...ts.infradead.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	"'Jingoo Han'" <jingoohan1@...il.com>
Subject: Re: [PATCH v11 17/19] drm: bridge: analogix/dp: expand the look time for waiting AUX CH reply

On Wednesday, December 16, 2015 12:58 PM, Yakir Yang wrote:
> 
> After test on rockchiop platform, i found sometims driver would failed
> at reading EDID message. After debugging more, i found that it's okay
> to read_a byte from i2c, but it would failed at AUX transcation if we
> try to ready multi-bytes from i2c.
> 
> Driver just can't received the AUX CH reply command, even no AUX error
> code. I may guess that the AUX wait time is not enough, so I try to
> expand the AUX wait time, and i do see this could fix the EDID read
> failed at rockchip platform.
> 
> And I thought that expand the wait time won't hurt Exynos platform too
> much, cause Exynos didn't have this problem, then driver would received
> the reply command very soon, so no more additional wait time would bring
> to Exynos platform.
> 
> Signed-off-by: Yakir Yang <ykk@...k-chips.com>
> ---
> Changes in v11: None
> Changes in v10: None
> Changes in v9: None
> Changes in v8: None
> Changes in v7: None
> Changes in v6: None
> Changes in v5: None
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
> 
>  drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> index c7e2959..dc376bd 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> @@ -482,7 +482,7 @@ int analogix_dp_start_aux_transaction(struct analogix_dp_device *dp)
>  	reg = readl(dp->reg_base + ANALOGIX_DP_INT_STA);
>  	while (!(reg & RPLY_RECEIV)) {
>  		timeout_loop++;
> -		if (DP_TIMEOUT_LOOP_COUNT < timeout_loop) {
> +		if (DP_TIMEOUT_LOOP_COUNT * 10 < timeout_loop) {

No, I hate this coding.
analogix_dp_reg.c is the common code that can be shared by various SoCs.
Please, find another way.

Best regards,
Jingoo Han


>  			dev_err(dp->dev, "AUX CH command reply failed!\n");
>  			return -ETIMEDOUT;
>  		}
> --
> 1.9.1


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