linux-kernel - Re: [Intel-gfx] [PATCH 05/21] drm/i915: Check eDP power when doing aux channel communications

Open Source and information security mailing list archives

Date:	Fri, 30 Sep 2011 19:02:42 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Keith Packard <keithp@...thp.com>
Cc:	Dave Airlie <airlied@...hat.com>, intel-gfx@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 05/21] drm/i915: Check eDP power when doing
 aux channel communications

On Thu, Sep 29, 2011 at 06:09:37PM -0700, Keith Packard wrote:
> Verify that the eDP VDD is on, either with the panel being on or with
> the VDD force-on bit being set.
> 
> This demonstrates that in many instances, VDD is not on when needed,
> which leads to failed EDID communications.
> 
> Signed-off-by: Keith Packard <keithp@...thp.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c |   22 ++++++++++++++++++++++
>  1 files changed, 22 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 8ab2a88..3b29a6f 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -279,6 +279,24 @@ intel_hrawclk(struct drm_device *dev)
>  	}
>  }
>  
> +static void
> +intel_dp_check_edp(struct intel_dp *intel_dp)
> +{
> +	struct drm_device *dev = intel_dp->base.base.dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	u32 pp_status, pp_control;
> +	if (!is_edp(intel_dp))
> +		return;
> +	pp_status = I915_READ(PCH_PP_STATUS);
> +	pp_control = I915_READ(PCH_PP_CONTROL);
> +	if ((pp_status & PP_ON) == 0 && (pp_control & EDP_FORCE_VDD) == 0) {
> +		WARN(1, "eDP powered off while attempting aux channel communication.\n");
> +		DRM_DEBUG_KMS("Status 0x%08x Control 0x%08x\n",
> +			      pp_status,
> +			      I915_READ(PCH_PP_CONTROL));

Use pp_control instead of re-reading?

> +	}
> +}
> +
>  static int
>  intel_dp_aux_ch(struct intel_dp *intel_dp,
>  		uint8_t *send, int send_bytes,
> @@ -295,6 +313,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
>  	uint32_t aux_clock_divider;
>  	int try, precharge;
>  
> +	intel_dp_check_edp(intel_dp);
>  	/* The clock divider is based off the hrawclk,
>  	 * and would like to run at 2MHz. So, take the
>  	 * hrawclk value and divide by 2 and use that

dp_aux_ch does the low-level io for the below, so either this one or the
below three hunks look a bit redundant.

> @@ -408,6 +427,7 @@ intel_dp_aux_native_write(struct intel_dp *intel_dp,
>  	int msg_bytes;
>  	uint8_t	ack;
>  
> +	intel_dp_check_edp(intel_dp);
>  	if (send_bytes > 16)
>  		return -1;
>  	msg[0] = AUX_NATIVE_WRITE << 4;
> @@ -450,6 +470,7 @@ intel_dp_aux_native_read(struct intel_dp *intel_dp,
>  	uint8_t ack;
>  	int ret;
>  
> +	intel_dp_check_edp(intel_dp);
>  	msg[0] = AUX_NATIVE_READ << 4;
>  	msg[1] = address >> 8;
>  	msg[2] = address & 0xff;
> @@ -493,6 +514,7 @@ intel_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
>  	int reply_bytes;
>  	int ret;
>  
> +	intel_dp_check_edp(intel_dp);
>  	/* Set up the command byte */
>  	if (mode & MODE_I2C_READ)
>  		msg[0] = AUX_I2C_READ << 4;
> -- 
> 1.7.6.3
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@...ts.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Mail: daniel@...ll.ch
Mobile: +41 (0)79 365 57 48
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