linux-kernel - Re: [PATCH v3 1/6] drm: bridge: dw-hdmi: Extract PHY interrupt setup to a function

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Message-ID: <295a8933-3baf-f0e6-636c-fb50be56c1d6@baylibre.com>
Date:   Wed, 8 Mar 2017 11:25:10 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Jose Abreu <Jose.Abreu@...opsys.com>,
        dri-devel@...ts.freedesktop.org,
        laurent.pinchart+renesas@...asonboard.com, architt@...eaurora.org
Cc:     kieran.bingham@...asonboard.com, linux-amlogic@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [PATCH v3 1/6] drm: bridge: dw-hdmi: Extract PHY interrupt setup
 to a function

Hi Jose,

On 03/07/2017 06:12 PM, Jose Abreu wrote:
> Hi Neil,
> 
> 
> On 07-03-2017 16:42, Neil Armstrong wrote:
>> From: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
>>
>> In preparation for adding PHY operations to handle RX SENSE and HPD,
>> group all the PHY interrupt setup code in a single location and extract
>> it to a separate function.
>>
>> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 50 ++++++++++++++-----------------
>>  1 file changed, 23 insertions(+), 27 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> index 026a0dc..1ed8bc1 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> @@ -1496,7 +1496,7 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi, struct drm_display_mode *mode)
>>  }
>>  
>>  /* Wait until we are registered to enable interrupts */
>> -static int dw_hdmi_fb_registered(struct dw_hdmi *hdmi)
>> +static void dw_hdmi_fb_registered(struct dw_hdmi *hdmi)
>>  {
>>  	hdmi_writeb(hdmi, HDMI_PHY_I2CM_INT_ADDR_DONE_POL,
>>  		    HDMI_PHY_I2CM_INT_ADDR);
>> @@ -1504,15 +1504,6 @@ static int dw_hdmi_fb_registered(struct dw_hdmi *hdmi)
>>  	hdmi_writeb(hdmi, HDMI_PHY_I2CM_CTLINT_ADDR_NAC_POL |
>>  		    HDMI_PHY_I2CM_CTLINT_ADDR_ARBITRATION_POL,
>>  		    HDMI_PHY_I2CM_CTLINT_ADDR);
>> -
>> -	/* enable cable hot plug irq */
>> -	hdmi_writeb(hdmi, hdmi->phy_mask, HDMI_PHY_MASK0);
>> -
>> -	/* Clear Hotplug interrupts */
>> -	hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE,
>> -		    HDMI_IH_PHY_STAT0);
>> -
>> -	return 0;
>>  }
>>  
>>  static void initialize_hdmi_ih_mutes(struct dw_hdmi *hdmi)
>> @@ -1630,6 +1621,26 @@ static void dw_hdmi_update_phy_mask(struct dw_hdmi *hdmi)
>>  		hdmi_writeb(hdmi, hdmi->phy_mask, HDMI_PHY_MASK0);
>>  }
>>  
>> +static void dw_hdmi_phy_setup_hpd(struct dw_hdmi *hdmi)
>> +{
>> +	/*
>> +	 * Configure the PHY RX SENSE and HPD interrupts polarities and clear
>> +	 * any pending interrupt.
>> +	 */
>> +	hdmi_writeb(hdmi, HDMI_PHY_HPD | HDMI_PHY_RX_SENSE, HDMI_PHY_POL0);
>> +	hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE,
>> +		    HDMI_IH_PHY_STAT0);
>> +
>> +	/* Enable cable hot plug irq. */
>> +	hdmi_writeb(hdmi, hdmi->phy_mask, HDMI_PHY_MASK0);
>> +
>> +	/* Clear and unmute interrupts. */
>> +	hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE,
>> +		    HDMI_IH_PHY_STAT0);
>> +	hdmi_writeb(hdmi, ~(HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE),
>> +		    HDMI_IH_MUTE_PHY_STAT0);
>> +}
>> +
>>  static enum drm_connector_status
>>  dw_hdmi_connector_detect(struct drm_connector *connector, bool force)
>>  {
>> @@ -2141,29 +2152,14 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
>>  			hdmi->ddc = NULL;
>>  	}
>>  
>> -	/*
>> -	 * Configure registers related to HDMI interrupt
>> -	 * generation before registering IRQ.
>> -	 */
> 
> 
> I've seen the databook and HPD interrupts are enabled per default
> (actually I think most of the interrupts are). I'm thinking
> whether we could get spurious interrupts because of not
> configuring HPD before registering IRQ (probably thats why the
> comment was there). How did you test this? I think that if you
> insert the cable before loading modules then you can try to
> emulate this condition. What do you think?

In fact the comment was wrong because it happened after the IRQ register,
and right before the IRQ register the initialize_hdmi_ih_mutes() is already
called to mute all the IRQ sources.
The previous rework moved the IRQ code, so this cleanup is welcome.

But indeed, I did not check this condition, I can try this.

Thanks,
Neil

> 
> Best regards,
> Jose Miguel Abreu
> 
>> -	hdmi_writeb(hdmi, HDMI_PHY_HPD | HDMI_PHY_RX_SENSE, HDMI_PHY_POL0);
>> -
>> -	/* Clear Hotplug interrupts */
>> -	hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE,
>> -		    HDMI_IH_PHY_STAT0);
>> -
>>  	hdmi->bridge.driver_private = hdmi;
>>  	hdmi->bridge.funcs = &dw_hdmi_bridge_funcs;
>>  #ifdef CONFIG_OF
>>  	hdmi->bridge.of_node = pdev->dev.of_node;
>>  #endif
>>  
>> -	ret = dw_hdmi_fb_registered(hdmi);
>> -	if (ret)
>> -		goto err_iahb;
>> -
>> -	/* Unmute interrupts */
>> -	hdmi_writeb(hdmi, ~(HDMI_IH_PHY_STAT0_HPD | HDMI_IH_PHY_STAT0_RX_SENSE),
>> -		    HDMI_IH_MUTE_PHY_STAT0);
>> +	dw_hdmi_fb_registered(hdmi);
>> +	dw_hdmi_phy_setup_hpd(hdmi);
>>  
>>  	memset(&pdevinfo, 0, sizeof(pdevinfo));
>>  	pdevinfo.parent = dev;