linux-kernel - Re: [RFC/RFT PATCH 2/4] drm/bridge: dw-hdmi: Add support for custom PHY handling

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Date:   Wed, 18 Jan 2017 12:20:43 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Jose Abreu <Jose.Abreu@...opsys.com>,
        dri-devel@...ts.freedesktop.org,
        laurent.pinchart+renesas@...asonboard.com
Cc:     linux-amlogic@...ts.infradead.org, kieran.bingham@...asonboard.com,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC/RFT PATCH 2/4] drm/bridge: dw-hdmi: Add support for custom
 PHY handling

Hi Jose,

On 01/18/2017 11:40 AM, Jose Abreu wrote:
> Hi Neil,
> 
> 
> On 17-01-2017 12:31, Neil Armstrong wrote:
>> @@ -1434,9 +1434,18 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi, struct drm_display_mode *mode)
>>  	hdmi_av_composer(hdmi, mode);
>>  
>>  	/* HDMI Initializateion Step B.2 */
>> -	ret = dw_hdmi_phy_init(hdmi);
>> -	if (ret)
>> -		return ret;
>> +	if (hdmi->plat_data->hdmi_phy_init) {
>> +		ret = hdmi->plat_data->hdmi_phy_init(hdmi, hdmi->plat_data,
>> @@ -1551,7 +1560,11 @@ static void dw_hdmi_poweron(struct dw_hdmi *hdmi)
>>  
>>  static void dw_hdmi_poweroff(struct dw_hdmi *hdmi)
>>  {
>> -	dw_hdmi_phy_disable(hdmi);
>> +	if (hdmi->phy_enabled && hdmi->plat_data->hdmi_phy_disable) {
>> +		hdmi->plat_data->hdmi_phy_disable(hdmi, hdmi->plat_data);
>> +		hdmi->phy_enabled = false;
>> +	} else
>> +		dw_hdmi_phy_disable(hdmi);
>>  	hdmi->bridge_is_on = false;
>>  }
>>  
>> @@ -1921,7 +1962,9 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
>>  		return -ENODEV;
>>  	}
>>  
>> -	if (!hdmi->phy->configure && !hdmi->plat_data->configure_phy) {
>> +	if (!hdmi->phy->configure &&
>> +	    !hdmi->plat_data->configure_phy &&
>> +	    !hdmi->plat_data->hdmi_phy_init) {
>>  		dev_err(hdmi->dev, "%s requires platform support\n",
>>  			hdmi->phy->name);
>>  		return -ENODEV;
>> @@ -2119,9 +2164,10 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
>> +	if (!hdmi->plat_data || !hdmi->plat_data->hdmi_read_hpd)
>> +		/* Unmute interrupts */
>> +		hdmi_writeb(hdmi, ~(HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE),
>> +			    HDMI_IH_MUTE_PHY_STAT0);
>>  
>>
> 
> [sniped some parts of the patch]
> 
> I personally don't like this kind of 'if plat_data ... else ...'
> Can't we just abstract all of the phy configuration (for a
> Synopsys Phy) to a new file and then pass it always in pdata as
> default? Then overwrite it with custom one if needed. Much like
> what you did with the regmap. Or even leave it in dw-hdmi.c but
> have a generic pdata structure with generic phy init/disable
> functions.

It's the idea we discussed with Laurent.
Keeping the Synopsys PHY code inside the dw-hdmi driver would be simpler.

But don't you think adding a proper "ops" structure apart from the plat_data
should be necessary ?

Neil

> 
> Best regards,
> Jose Miguel Abreu
>