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

From: "Jingoo Han" <jingoohan1@gmail.com>
To: 'Yakir Yang' <ykk@rock-chips.com>,
	'Inki Dae' <inki.dae@samsung.com>,
	'Mark Yao' <mark.yao@rock-chips.com>,
	'Heiko Stuebner' <heiko@sntech.de>
Cc: devicetree@vger.kernel.org,
	'Krzysztof Kozlowski' <k.kozlowski@samsung.com>,
	linux-samsung-soc@vger.kernel.org,
	'Russell King' <linux@arm.linux.org.uk>,
	linux-rockchip@lists.infradead.org,
	'Jingoo Han' <jingoohan1@gmail.com>,
	emil.l.velikov@gmail.com, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	'Kishon Vijay Abraham I' <kishon@ti.com>,
	javier@osg.samsung.com, 'Rob Herring' <robh+dt@kernel.org>,
	'Andy Yan' <andy.yan@rock-chips.com>,
	'Thierry Reding' <treding@nvidia.com>,
	'Gustavo Padovan' <gustavo.padovan@collabora.co.uk>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v11 17/19] drm: bridge: analogix/dp: expand the look time for waiting AUX CH reply
Date: Tue, 22 Dec 2015 21:26:52 +0900	[thread overview]
Message-ID: <000a01d13cb4$0f81f510$2e85df30$@com> (raw)
In-Reply-To: <1450238257-3274-1-git-send-email-ykk@rock-chips.com>

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@rock-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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