Re: [PATCH 4/4] drm/i915: Get HW state changes required for DSI port C

From: "Singh, Gaurav K" <gaurav.k.singh@intel.com>
To: Jani Nikula <jani.nikula@linux.intel.com>,
	intel-gfx <intel-gfx@lists.freedesktop.org>
Cc: Shobhit Kumar <shobhit.kumar@intel.com>
Subject: Re: [PATCH 4/4] drm/i915: Get HW state changes required for	DSI port C
Date: Mon, 08 Dec 2014 18:43:04 +0530	[thread overview]
Message-ID: <5485A3E0.3080302@intel.com> (raw)
In-Reply-To: <87wq62mkxt.fsf@intel.com>

On 12/8/2014 5:07 PM, Jani Nikula wrote:
> On Sun, 07 Dec 2014, Gaurav K Singh <gaurav.k.singh@intel.com> wrote:
>> Due to some hardware limitations, MIPI Port C DPI Enable bit
>> does not get set. To check whether DSI Port C was enabled in BIOS,
>> check the Pipe B enable bit for DSI Port C. In hardware, DSI Port C
>> is linked with Pipe B.
> "due to some hardware limitations" is awfully vague. The same code will
> be used on many platforms; I doubt this applies to all of them. Is there
> a workaround name for this?
>
> BR,
> Jani.

Hi Jani,

This is currently only for BYT, I missed to add in this patch commit header.

Software workaround for getting the HW status of DSI Port C on BYT, will 
it be fine if I include this in the commit header.

With regards,
Gaurav
>
>> Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_dsi.c |   21 ++++++++++++++++-----
>>   1 file changed, 16 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
>> index 215d004..0334c4d 100644
>> --- a/drivers/gpu/drm/i915/intel_dsi.c
>> +++ b/drivers/gpu/drm/i915/intel_dsi.c
>> @@ -398,8 +398,9 @@ static bool intel_dsi_get_hw_state(struct intel_encoder *encoder,
>>   				   enum pipe *pipe)
>>   {
>>   	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
>> +	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
>>   	enum intel_display_power_domain power_domain;
>> -	u32 port_ctl, func;
>> +	u32 dsi_status, func;
>>   	enum port port;
>>   
>>   	DRM_DEBUG_KMS("\n");
>> @@ -409,13 +410,23 @@ static bool intel_dsi_get_hw_state(struct intel_encoder *encoder,
>>   		return false;
>>   
>>   	/* XXX: this only works for one DSI output */
>> -	for_each_dsi_port(port, (1 << PORT_A) | (1 << PORT_C)) {
>> -		port_ctl = I915_READ(MIPI_PORT_CTRL(port));
>> +	for_each_dsi_port(port, intel_dsi->ports) {
>>   		func = I915_READ(MIPI_DSI_FUNC_PRG(port));
>>   
>> -		if ((port_ctl & DPI_ENABLE) || (func & CMD_MODE_DATA_WIDTH_MASK)) {
>> +		/* Due to some hardware limitations, MIPI Port C DPI Enable
>> +		 * bit does not get set. To check whether DSI Port C was
>> +		 * enabled in BIOS, check the Pipe B enable bit
>> +		 */
>> +		if (port == PORT_C)
>> +			dsi_status = I915_READ(PIPECONF(PIPE_B)) &
>> +							PIPECONF_ENABLE;
>> +		else
>> +			dsi_status = I915_READ(MIPI_PORT_CTRL(port)) &
>> +							DPI_ENABLE;
>> +
>> +		if (dsi_status || (func & CMD_MODE_DATA_WIDTH_MASK)) {
>>   			if (I915_READ(MIPI_DEVICE_READY(port)) & DEVICE_READY) {
>> -				*pipe = port == PORT_A ? PIPE_A : PIPE_C;
>> +				*pipe = port == PORT_A ? PIPE_A : PIPE_B;
>>   				return true;
>>   			}
>>   		}
>> -- 
>> 1.7.9.5
>>
>> _______________________________________________
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>> Intel-gfx@lists.freedesktop.org
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