Re: [RFC][PATCH] drm: adv7511/33: Fix adv7511_cec_init() failure handling

From: Archit Taneja <architt@codeaurora.org>
To: John Stultz <john.stultz@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	David Airlie <airlied@linux.ie>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Bhumika Goyal <bhumirks@gmail.com>,
	Inki Dae <inki.dae@samsung.com>,
	dri-devel@lists.freedesktop.org,
	lkml <linux-kernel@vger.kernel.org>,
	Xinliang Liu <xinliang.liu@linaro.org>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Sean Paul <seanpaul@chromium.org>,
	Hans Verkuil <hans.verkuil@cisco.com>,
	Guodong Xu <guodong.xu@linaro.org>
Subject: Re: [RFC][PATCH] drm: adv7511/33: Fix adv7511_cec_init() failure handling
Date: Wed, 29 Nov 2017 10:35:54 +0530	[thread overview]
Message-ID: <deab5e2a-0e49-6954-2734-ec52aa61ff3d@codeaurora.org> (raw)
In-Reply-To: <CALAqxLU+jo-F_8Q7n72CP5gQO1JhRiQZaWGSn=q57v9Ofiv8fg@mail.gmail.com>

On 11/29/2017 03:02 AM, John Stultz wrote:
> On Sun, Nov 26, 2017 at 4:56 AM, Archit Taneja <architt@codeaurora.org> wrote:
>>
>> On 11/17/2017 04:29 AM, John Stultz wrote:
>>> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>>> b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>>> index 0e14f15..939c3b9 100644
>>> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>>> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>>> @@ -1203,12 +1203,12 @@ static int adv7511_probe(struct i2c_client *i2c,
>>> const struct i2c_device_id *id)
>>>      #ifdef CONFIG_DRM_I2C_ADV7511_CEC
>>>          ret = adv7511_cec_init(dev, adv7511, offset);
>>> -       if (ret)
>>> -               goto err_unregister_cec;
>>>    #else
>>> -       regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset,
>>> -                    ADV7511_CEC_CTRL_POWER_DOWN);
>>> +       ret = 1;
>>>    #endif
>>> +       if (ret)
>>> +               regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL +
>>> offset,
>>> +                            ADV7511_CEC_CTRL_POWER_DOWN);
>>
>>
>> This would force CEC to be powered off even if adv7511_cec_init() returned
>> 0, right?
> 
> I don't think so. The initent was its only powered off if
> adv7511_cec_init returns an error or if  CONFIG_DRM_I2C_ADV7511_CEC is
> not set.
> 
>> Do we know why the call to adv7511_cec_init() is failing on the Hikey board?
>> If it's
>> because there isn't a "cec" clock specified in DT, it's not really a fatal
>> error, it
>> just means that the platform hasn't been set up to support CEC. In that
> 
> Yea. I believe this is the case w/ HiKey.  I don't have deeply
> detailed docs on the board so I'm not sure if we will be able to
> enable that or not (Xinliang/Guodong: Do you know if its possible?).
> In the meantime though, we shouldn't regress.
> 
>> case, we
>> should just power down the CEC block. So, if adv7511_cec_init() would return
>> a
>> -ENOENT, which we could use as a hint to power down CEC. So, maybe something
>> like this?:
>>
>> #ifdef CONFIG_DRM_I2C_ADV7511_CEC
>>          ret = adv7511_cec_init(dev, adv7511, offset);
>>          if (ret && ret != -ENOENT)
>>                  goto err_unregister_cec;
>> #endif
>>          if (ret)
>>              regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset,
>>                          ADV7511_CEC_CTRL_POWER_DOWN);
>>
>> Apart from this, we should also move adv7511_cec_init() up in the probe so
>> that
>> it's called before the drm_bridge is registered.
> 
> Hans has since reworked the patch w/ a new version. You might want to
> check his patches and see if they fit what your imagining.

Yes, I saw Hans's patch after I wrote to you. That patch looks perfect. I'll
queue that to the drm-misc repo once it's rebased on 4.15-rc1.

Thanks,
Archit

> 
> thanks
> -john
> 

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