Re: [PATCH 1/2] drm/i915/bxt: Set oscaledcompmethod to enable scale value

[Imre Deak <imre.deak@intel.com>]

On Wed, 2015-09-23 at 00:01 +0530, Sivakumar Thulasimani wrote:
> 
> On 9/22/2015 6:32 PM, Imre Deak wrote:
> > On ma, 2015-09-21 at 23:00 +0530, Sivakumar Thulasimani wrote:
> >> Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
> >>
> >> On 9/18/2015 2:11 PM, Sonika Jindal wrote:
> >>> Bspec update tells that we have to enable oscaledcompmethod instead of
> >>> ouniqetrangenmethod for enabling scale value during swing programming.
> >>> Also, scale value is 'don't care' for other levels except the last entry
> >>> translation table. So, make it 0 instead of 0x9A.
> >>>
> >>> Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
> >>> ---
> >>>    drivers/gpu/drm/i915/i915_reg.h  |    2 +-
> >>>    drivers/gpu/drm/i915/intel_ddi.c |   22 +++++++++++-----------
> >>>    2 files changed, 12 insertions(+), 12 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> >>> index 812b7b2..cec6546 100644
> >>> --- a/drivers/gpu/drm/i915/i915_reg.h
> >>> +++ b/drivers/gpu/drm/i915/i915_reg.h
> >>> @@ -1395,7 +1395,7 @@ enum skl_disp_power_wells {
> >>>    #define BXT_PORT_TX_DW3_LN0(port)	_PORT3(port, _PORT_TX_DW3_LN0_A,  \
> >>>    						     _PORT_TX_DW3_LN0_B,  \
> >>>    						     _PORT_TX_DW3_LN0_C)
> >>> -#define   UNIQE_TRANGE_EN_METHOD	(1 << 27)
> >>> +#define   SCALE_DCOMP_METHOD		(1 << 26)
> >>>    
> >>>    #define _PORT_TX_DW4_LN0_A		0x162510
> >>>    #define _PORT_TX_DW4_LN0_B		0x6C510
> >>> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> >>> index fec51df..0d9b304 100644
> >>> --- a/drivers/gpu/drm/i915/intel_ddi.c
> >>> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> >>> @@ -261,15 +261,15 @@ struct bxt_ddi_buf_trans {
> >>>     */
> >>>    static const struct bxt_ddi_buf_trans bxt_ddi_translations_dp[] = {
> >>>    					/* Idx	NT mV diff	db  */
> >>> -	{ 52,  0x9A, 0, 128, true  },	/* 0:	400		0   */
> >>> -	{ 78,  0x9A, 0, 85,  false },	/* 1:	400		3.5 */
> >>> -	{ 104, 0x9A, 0, 64,  false },	/* 2:	400		6   */
> >>> -	{ 154, 0x9A, 0, 43,  false },	/* 3:	400		9.5 */
> >>> -	{ 77,  0x9A, 0, 128, false },	/* 4:	600		0   */
> >>> -	{ 116, 0x9A, 0, 85,  false },	/* 5:	600		3.5 */
> >>> -	{ 154, 0x9A, 0, 64,  false },	/* 6:	600		6   */
> >>> -	{ 102, 0x9A, 0, 128, false },	/* 7:	800		0   */
> >>> -	{ 154, 0x9A, 0, 85,  false },	/* 8:	800		3.5 */
> >>> +	{ 52,  0, 0, 128, true  },	/* 0:	400		0   */
> >>> +	{ 78,  0, 0, 85,  false },	/* 1:	400		3.5 */
> >>> +	{ 104, 0, 0, 64,  false },	/* 2:	400		6   */
> >>> +	{ 154, 0, 0, 43,  false },	/* 3:	400		9.5 */
> >>> +	{ 77,  0, 0, 128, false },	/* 4:	600		0   */
> >>> +	{ 116, 0, 0, 85,  false },	/* 5:	600		3.5 */
> >>> +	{ 154, 0, 0, 64,  false },	/* 6:	600		6   */
> >>> +	{ 102, 0, 0, 128, false },	/* 7:	800		0   */
> >>> +	{ 154, 0, 0, 85,  false },	/* 8:	800		3.5 */
> > There is no point in changing the above values as they are don't-care in
> > any case. In fact the reset value is 0x98 so I'd program that for these
> > cases if we ever wanted to change them. For now I'd leave this as-is to
> > keep in sync with the bxt_ddi_translations_hdmi table and also what CHV
> > does.
> >
> >>>    	{ 154, 0x9A, 1, 128, false },	/* 9:	1200		0   */
> >>>    };
> >
> >>>    
> >>> @@ -2151,9 +2151,9 @@ static void bxt_ddi_vswing_sequence(struct drm_device *dev, u32 level,
> >>>    	I915_WRITE(BXT_PORT_TX_DW2_GRP(port), val);
> >>>    
> >>>    	val = I915_READ(BXT_PORT_TX_DW3_LN0(port));
> >>> -	val &= ~UNIQE_TRANGE_EN_METHOD;
> >>> +	val &= ~SCALE_DCOMP_METHOD;
> >>>    	if (ddi_translations[level].enable)
> >>> -		val |= UNIQE_TRANGE_EN_METHOD;
> >>> +		val |= SCALE_DCOMP_METHOD;
> > Please still leave behind a DRM_ERROR in case UNIQE_TRANGE_EN_METHOD was
> > set in the register and we are disabling scaling. The scaling value does
> > seem to depend on this bit too, so seeing if it was set can help
> > tracking down problems.
> >
> This was the only place UNIQE_TRANGE_EN_METHOD was set before, with that 
> removed
> only possibility for it to be set is by GOP/VBIOS. (who are also 
> expected to make this change
> if not done already.) in such a scenario wont an error message be 
> useless here ?

Yes, this is exactly a check for BIOS settings. It wouldn't be the first
case that BIOS didn't program something according to our expectations,
especially given the multiple versions out there. 

> >>>    	I915_WRITE(BXT_PORT_TX_DW3_GRP(port), val);
> >>>    
> >>>    	val = I915_READ(BXT_PORT_TX_DW4_LN0(port));
> >
> >
> >
> 
> 


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