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

Open Source and information security mailing list archives

Date:	Wed, 23 Dec 2015 14:00:34 +0800
From:	Yakir Yang <ykk@...k-chips.com>
To:	Jingoo Han <jingoohan1@...il.com>,
	'Inki Dae' <inki.dae@...sung.com>,
	'Mark Yao' <mark.yao@...k-chips.com>,
	'Heiko Stuebner' <heiko@...ech.de>
Cc:	devicetree@...r.kernel.org,
	'Krzysztof Kozlowski' <k.kozlowski@...sung.com>,
	linux-samsung-soc@...r.kernel.org,
	'Russell King' <linux@....linux.org.uk>,
	linux-rockchip@...ts.infradead.org, emil.l.velikov@...il.com,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	'Kishon Vijay Abraham I' <kishon@...com>,
	javier@....samsung.com, 'Rob Herring' <robh+dt@...nel.org>,
	'Andy Yan' <andy.yan@...k-chips.com>,
	'Thierry Reding' <treding@...dia.com>,
	'Gustavo Padovan' <gustavo.padovan@...labora.co.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v11 17/19] drm: bridge: analogix/dp: expand the look time
 for waiting AUX CH reply

Hi Jingoo,

On 12/23/2015 12:24 PM, Yakir Yang wrote:
> Hi Jingoo,
>
> On 12/22/2015 08:26 PM, Jingoo Han wrote:
>> 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.
>
> Okay, I have double checked that i do have this problem in my side. 
> Hmmm.....
> I thought it's okay for you if I expand the "DP_TIMEOUT_LOOP_COUNT" 
> directly,
> it 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.
>

Oh, sorry, little mistaken, I mean, is it okay for you to expand the 
"DP_TIMEOUT_LOOP_COUNT" directly ?

- Yakir

> And actually the datasheet haven't described the spec of aux reply 
> delay time.
>
> Thanks,
> - Yakir
>
>> Best regards,
>> Jingoo Han
>>
>>
>>>               dev_err(dp->dev, "AUX CH command reply failed!\n");
>>>               return -ETIMEDOUT;
>>>           }
>>> -- 
>>> 1.9.1
>>
>>
>>
>>
>
>
>
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip
>
>
>

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