Re: [PATCH] drm/i915: Changes required to enable DSI Video Mode on CHT

["Singh, Gaurav K" <gaurav.k.singh@intel.com>]

On 12/12/2014 1:03 PM, Singh, Gaurav K wrote:
>
> On 12/10/2014 7:38 PM, Gaurav K Singh wrote:
>> For CHT changes are required for calculating the correct m,n & p with
>> minimal error +/- for the required DSI clock, so that the correct 
>> dividor
>> & ctrl values are written in cck regs for DSI. This patch has been 
>> tested
>> on CHT RVP with 1200 x 1920 panel.
>>
>> Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_dsi_pll.c |   43 
>> ++++++++++++++++++++++++++--------
>>   1 file changed, 33 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c 
>> b/drivers/gpu/drm/i915/intel_dsi_pll.c
>> index 8957f10..9236b66 100644
>> --- a/drivers/gpu/drm/i915/intel_dsi_pll.c
>> +++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
>> @@ -162,7 +162,8 @@ static u32 dsi_clk_from_pclk(u32 pclk, int 
>> pixel_format, int lane_count)
>>     #endif
>>   -static int dsi_calc_mnp(u32 dsi_clk, struct dsi_mnp *dsi_mnp)
>> +static int dsi_calc_mnp(struct drm_i915_private *dev_priv,
>> +            u32 dsi_clk, struct dsi_mnp *dsi_mnp)
>>   {
>>       u32 m, n, p;
>>       u32 ref_clk;
>> @@ -173,6 +174,10 @@ static int dsi_calc_mnp(u32 dsi_clk, struct 
>> dsi_mnp *dsi_mnp)
>>       u32 calc_m;
>>       u32 calc_p;
>>       u32 m_seed;
>> +    u32 m_start;
>> +    u32 m_limit;
>> +    u32 n_limit;
>> +    u32 p_limit;
>>         /* dsi_clk is expected in KHZ */
>>       if (dsi_clk < 300000 || dsi_clk > 1150000) {
>> @@ -180,18 +185,33 @@ static int dsi_calc_mnp(u32 dsi_clk, struct 
>> dsi_mnp *dsi_mnp)
>>           return -ECHRNG;
>>       }
>>   -    ref_clk = 25000;
>> +    if (IS_CHERRYVIEW(dev_priv->dev)) {
>> +        ref_clk = 100000;
>> +        m_start = 70;
>> +        m_limit = 96;
>> +        n_limit = 4;
>> +        p_limit = 6;
>> +    } else if (IS_VALLEYVIEW(dev_priv->dev)) {
>> +        ref_clk = 25000;
>> +        m_start = 62;
>> +        m_limit = 92;
>> +        n_limit = 1;
>> +        p_limit = 6;
>> +    } else {
>> +        DRM_ERROR("Unsupported device\n");
>> +        return -ENODEV;
>> +    }
>>       target_dsi_clk = dsi_clk;
>>       error = 0xFFFFFFFF;
>>       tmp_error = 0xFFFFFFFF;
>>       calc_m = 0;
>>       calc_p = 0;
>>   -    for (m = 62; m <= 92; m++) {
>> -        for (p = 2; p <= 6; p++) {
>> +    for (m = m_start; m <= m_limit; m++) {
>> +        for (p = 2; p <= p_limit; p++) {
>>               /* Find the optimal m and p divisors
>>                  with minimal error +/- the required clock */
>> -            calc_dsi_clk = (m * ref_clk) / p;
>> +            calc_dsi_clk = (m * ref_clk) / (p * n_limit);
>>               if (calc_dsi_clk == target_dsi_clk) {
>>                   calc_m = m;
>>                   calc_p = p;
>> @@ -212,11 +232,14 @@ static int dsi_calc_mnp(u32 dsi_clk, struct 
>> dsi_mnp *dsi_mnp)
>>       }
>>         m_seed = lfsr_converts[calc_m - 62];
>> -    n = 1;
>> +    n = n_limit;
>>       dsi_mnp->dsi_pll_ctrl = 1 << (DSI_PLL_P1_POST_DIV_SHIFT + 
>> calc_p - 2);
>> -    dsi_mnp->dsi_pll_div = (n - 1) << DSI_PLL_N1_DIV_SHIFT |
>> -        m_seed << DSI_PLL_M1_DIV_SHIFT;
>> -
>> +    if (IS_CHERRYVIEW(dev_priv->dev))
>> +        dsi_mnp->dsi_pll_div = (n/2) << DSI_PLL_N1_DIV_SHIFT |
>> +                m_seed << DSI_PLL_M1_DIV_SHIFT;
>> +    else
>> +        dsi_mnp->dsi_pll_div = (n - 1) << DSI_PLL_N1_DIV_SHIFT |
>> +                m_seed << DSI_PLL_M1_DIV_SHIFT;
>>       return 0;
>>   }
>>   @@ -235,7 +258,7 @@ static void vlv_configure_dsi_pll(struct 
>> intel_encoder *encoder)
>>       dsi_clk = dsi_clk_from_pclk(intel_dsi->pclk, 
>> intel_dsi->pixel_format,
>>                       intel_dsi->lane_count);
>>   -    ret = dsi_calc_mnp(dsi_clk, &dsi_mnp);
>> +    ret = dsi_calc_mnp(dev_priv, dsi_clk, &dsi_mnp);
>>       if (ret) {
>>           DRM_DEBUG_KMS("dsi_calc_mnp failed\n");
>>           return;
> Hi Jani,
>
> Could you please review this patch?
>
> With regards,
> Gaurav
>
Hi Jani,

Could you please review this patch?

With regards,
Gaurav
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