linux-kernel - Re: [PATCH v8 4/8] drm/rockchip: dw-mipi-dsi: Fix error handling path

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Message-ID: <a3140d3d-d6bc-afa9-30fa-00980511dd82@collabora.com>
Date:   Fri, 2 Mar 2018 13:22:53 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Heiko Stuebner <heiko@...ech.de>
Cc:     dri-devel@...ts.freedesktop.org, Rob Herring <robh+dt@...nel.org>,
        Archit Taneja <architt@...eaurora.org>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sandy Huang <hjc@...k-chips.com>,
        linux-rockchip@...ts.infradead.org,
        Jeffy Chen <jeffy.chen@...k-chips.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 4/8] drm/rockchip: dw-mipi-dsi: Fix error handling path

Hi Heiko,

On 02/03/18 13:17, Heiko Stuebner wrote:
> Hi Enric,
> 
> Am Freitag, 2. März 2018, 13:09:02 CET schrieb Enric Balletbo i Serra:
>> Hi Heiko,
>>
>> On 01/03/18 16:50, Heiko Stübner wrote:
>>> Hi Jeffy, Thierry, Enric,
>>>
>>> Am Mittwoch, 10. Januar 2018, 17:23:44 CET schrieb Thierry Escande:
>>>> From: Jeffy Chen <jeffy.chen@...k-chips.com>
>>>>
>>>> Add missing pm_runtime_disable() in bind()'s error handling path.
>>>>
>>>> Also cleanup encoder & connector in unbind().
>>>
>>> Can you please split all these surprise "Also" sections into separate
>>> patches?
>>>
>>
>> I'll take a look.
>>
>>> It looks like this is true for all following patch to some degree and
>>> the inno-hdmi patch even has a unbind reordering-change without
>>> mentioning it in the commit message.
>>>
>>
>> Actually, I think this patch is not correct against current mainline, see below.
>>
>>>
>>> Thanks
>>> Heiko
>>>
>>>> Fixes: 80a9a059d4e4 ("drm/rockchip/dsi: add dw-mipi power domain support")
>>>> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
>>>> Signed-off-by: Thierry Escande <thierry.escande@...labora.com>
>>>> ---
>>>>  drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 21 +++++++++++++--------
>>>>  1 file changed, 13 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
>>>> b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c index b1fe0639227e..78e6b7919bf7
>>>> 100644
>>>> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
>>>> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
>>>> @@ -1282,7 +1282,7 @@ static int dw_mipi_dsi_bind(struct device *dev, struct
>>>> device *master, ret = dw_mipi_dsi_register(drm, dsi);
>>>>  	if (ret) {
>>>>  		DRM_DEV_ERROR(dev, "Failed to register mipi_dsi: %d\n", ret);
>>>> -		goto err_pllref;
>>>> +		goto err_disable_pllref;
>>>>  	}
>>>>
>>>>  	dsi->dsi_host.ops = &dw_mipi_dsi_host_ops;
>>>> @@ -1290,24 +1290,25 @@ static int dw_mipi_dsi_bind(struct device *dev,
>>>> struct device *master, ret = mipi_dsi_host_register(&dsi->dsi_host);
>>>>  	if (ret) {
>>>>  		DRM_DEV_ERROR(dev, "Failed to register MIPI host: %d\n", ret);
>>>> -		goto err_cleanup;
>>>> +		goto err_disable_pm_runtime;
>>>>  	}
>>>>
>>>>  	if (!dsi->panel) {
>>>>  		ret = -EPROBE_DEFER;
>>>> -		goto err_mipi_dsi_host;
>>>> +		goto err_unreg_mipi_dsi_host;
>>>>  	}
>>>>
>>>>  	dev_set_drvdata(dev, dsi);
>>>>  	pm_runtime_enable(dev);
>>>>  	return 0;
>>>>
>>>> -err_mipi_dsi_host:
>>>> +err_unreg_mipi_dsi_host:
>>>>  	mipi_dsi_host_unregister(&dsi->dsi_host);
>>>> -err_cleanup:
>>>> -	drm_encoder_cleanup(&dsi->encoder);
>>>> -	drm_connector_cleanup(&dsi->connector);
>>>> -err_pllref:
>>>> +err_disable_pm_runtime:
>>>> +	pm_runtime_disable(dev);
>>
>> I think that this is not required, 'pm_runtime_enable' is called just before the
>> 'return 0' (see above). Commit 517f56839f58 'drm/rockchip: dw-mipi-dsi: fix
>> possible un-balanced runtime PM enable' moved the call to that place. So, now
>> the call to pm_runtime_disable is not needed.
>>
>>>> +	dsi->connector.funcs->destroy(&dsi->connector);
>>>> +	dsi->encoder.funcs->destroy(&dsi->encoder);
>>
>> Here, there is a reordering and also a function replacement. The reorder makes
>> sense to me, first cleanup the connector and then the encoder, but I'm not sure
>> about the function change and if is needed, anyway, in the case is needed,
>> shouldn't be
>>
>> +	drm_connector_cleanup(&dsi->connector);
>> +	drm_encoder_cleanup(&dsi->encoder);
>>
>> instead?
> 
> If you look at drm/rockchip/dw-mipi-dsi.c you'll see that
> dw_mipi_dsi_drm_connector_destroy() does both connector_unregister()
> and drm_connector_cleanup().
> 
> And looking at other drivers it really seems that calling that destroy
> callback is really the way to go.
> 

Right, thanks for pointing me in the right direction. Learning about this
graphics stuff ;)

Regards,
 Enric
> 
> Heiko
>