linux-kernel - Re: [PATCH v3] drm: bridge: synopsys/dw-hdmi: Enable cec clock

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Date:   Fri, 24 Nov 2017 09:41:16 +0100
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Archit Taneja <architt@...eaurora.org>,
        Pierre-Hugues Husson <phh@....me>,
        linux-rockchip@...ts.infradead.org
Cc:     heiko@...ech.de, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        linux@...linux.org.uk, Andrzej Hajda <a.hajda@...sung.com>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v3] drm: bridge: synopsys/dw-hdmi: Enable cec clock

On 11/24/2017 09:04 AM, Archit Taneja wrote:
> Hi,
> 
> On 11/20/2017 06:00 PM, Hans Verkuil wrote:
>> I didn't see this merged for 4.15, is it too late to include this?
>> All other changes needed to get CEC to work on rk3288 and rk3399 are all merged.
> 
> Sorry for the late reply. I was out last week.
> 
> Dave recently sent the second pull request for 4.15, so I think it would be hard to get it
> in the merge window now. We could target it for the 4.15-rcs since it is preventing the
> feature from working. Is it possible to rephrase the commit message a bit so that it's clear
> that we need it for CEC to work?

While it is not my patch I would propose something like this:

"Support the "cec" optional clock. The documentation already mentions "cec"
optional clock and it is used by several boards, but currently the driver
doesn't enable it, thus preventing cec from working on those boards.

And even worse: a /dev/cecX device will appear for those boards, but it
won't be functioning without configuring this clock."

I hadn't realized that last sentence until I started thinking about it,
but this patch is really needed.

Regards,

	Hans

> 
> Thanks,
> Archit
> 
>>
>> Regards,
>>
>> 	Hans
>>
>> On 10/26/2017 08:19 PM, Pierre-Hugues Husson wrote:
>>> The documentation already mentions "cec" optional clock, but
>>> currently the driver doesn't enable it.
>>>
>>> Changes:
>>> v3:
>>> - Drop useless braces
>>>
>>> v2:
>>> - Separate ENOENT errors from others
>>> - Propagate other errors (especially -EPROBE_DEFER)
>>>
>>> Signed-off-by: Pierre-Hugues Husson <phh@....me>
>>> ---
>>>   drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 25 +++++++++++++++++++++++++
>>>   1 file changed, 25 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>>> index bf14214fa464..d82b9747a979 100644
>>> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>>> @@ -138,6 +138,7 @@ struct dw_hdmi {
>>>   	struct device *dev;
>>>   	struct clk *isfr_clk;
>>>   	struct clk *iahb_clk;
>>> +	struct clk *cec_clk;
>>>   	struct dw_hdmi_i2c *i2c;
>>>   
>>>   	struct hdmi_data_info hdmi_data;
>>> @@ -2382,6 +2383,26 @@ __dw_hdmi_probe(struct platform_device *pdev,
>>>   		goto err_isfr;
>>>   	}
>>>   
>>> +	hdmi->cec_clk = devm_clk_get(hdmi->dev, "cec");
>>> +	if (PTR_ERR(hdmi->cec_clk) == -ENOENT) {
>>> +		hdmi->cec_clk = NULL;
>>> +	} else if (IS_ERR(hdmi->cec_clk)) {
>>> +		ret = PTR_ERR(hdmi->cec_clk);
>>> +		if (ret != -EPROBE_DEFER)
>>> +			dev_err(hdmi->dev, "Cannot get HDMI cec clock: %d\n",
>>> +					ret);
>>> +
>>> +		hdmi->cec_clk = NULL;
>>> +		goto err_iahb;
>>> +	} else {
>>> +		ret = clk_prepare_enable(hdmi->cec_clk);
>>> +		if (ret) {
>>> +			dev_err(hdmi->dev, "Cannot enable HDMI cec clock: %d\n",
>>> +					ret);
>>> +			goto err_iahb;
>>> +		}
>>> +	}
>>> +
>>>   	/* Product and revision IDs */
>>>   	hdmi->version = (hdmi_readb(hdmi, HDMI_DESIGN_ID) << 8)
>>>   		      | (hdmi_readb(hdmi, HDMI_REVISION_ID) << 0);
>>> @@ -2518,6 +2539,8 @@ __dw_hdmi_probe(struct platform_device *pdev,
>>>   		cec_notifier_put(hdmi->cec_notifier);
>>>   
>>>   	clk_disable_unprepare(hdmi->iahb_clk);
>>> +	if (hdmi->cec_clk)
>>> +		clk_disable_unprepare(hdmi->cec_clk);
>>>   err_isfr:
>>>   	clk_disable_unprepare(hdmi->isfr_clk);
>>>   err_res:
>>> @@ -2541,6 +2564,8 @@ static void __dw_hdmi_remove(struct dw_hdmi *hdmi)
>>>   
>>>   	clk_disable_unprepare(hdmi->iahb_clk);
>>>   	clk_disable_unprepare(hdmi->isfr_clk);
>>> +	if (hdmi->cec_clk)
>>> +		clk_disable_unprepare(hdmi->cec_clk);
>>>   
>>>   	if (hdmi->i2c)
>>>   		i2c_del_adapter(&hdmi->i2c->adap);
>>>
>>
>