[PATCH 1/2] drm/msm/dsi: add a helper method to compute the dsi byte clk

[Abhinav Kumar]

On 1/9/2023 6:25 PM, Dmitry Baryshkov wrote:
> On 10/01/2023 04:21, Abhinav Kumar wrote:
>>
>>
>> On 1/9/2023 5:34 PM, Dmitry Baryshkov wrote:
>>> On 22/09/2022 03:49, Abhinav Kumar wrote:
>>>> Re-arrange the dsi_calc_pclk method to two helpers, one to
>>>> compute the DSI byte clk and the other to compute the pclk.
>>>>
>>>> This makes the separation of the two clean and also allows
>>>> clients to compute and use the dsi byte clk separately.
>>>>
>>>> Signed-off-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>>>> ---
>>>>   drivers/gpu/drm/msm/dsi/dsi.h      |  2 ++
>>>>   drivers/gpu/drm/msm/dsi/dsi_host.c | 27 +++++++++++++++++++--------
>>>>   2 files changed, 21 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi.h 
>>>> b/drivers/gpu/drm/msm/dsi/dsi.h
>>>> index 2a96b4fe7839..60ba8e67f550 100644
>>>> --- a/drivers/gpu/drm/msm/dsi/dsi.h
>>>> +++ b/drivers/gpu/drm/msm/dsi/dsi.h
>>>> @@ -118,6 +118,8 @@ int dsi_link_clk_enable_6g(struct msm_dsi_host 
>>>> *msm_host);
>>>>   int dsi_link_clk_enable_v2(struct msm_dsi_host *msm_host);
>>>>   void dsi_link_clk_disable_6g(struct msm_dsi_host *msm_host);
>>>>   void dsi_link_clk_disable_v2(struct msm_dsi_host *msm_host);
>>>> +unsigned long dsi_byte_clk_get_rate(struct mipi_dsi_host *host, 
>>>> bool is_bonded_dsi,
>>>> +        const struct drm_display_mode *mode);
>>>>   int dsi_tx_buf_alloc_6g(struct msm_dsi_host *msm_host, int size);
>>>>   int dsi_tx_buf_alloc_v2(struct msm_dsi_host *msm_host, int size);
>>>>   void *dsi_tx_buf_get_6g(struct msm_dsi_host *msm_host);
>>>> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c 
>>>> b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> index 57a4c0fa614b..32b35d4ac1d3 100644
>>>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>>>> @@ -569,9 +569,8 @@ void dsi_link_clk_disable_v2(struct msm_dsi_host 
>>>> *msm_host)
>>>>       clk_disable_unprepare(msm_host->byte_clk);
>>>>   }
>>>> -static unsigned long dsi_get_pclk_rate(struct msm_dsi_host 
>>>> *msm_host, bool is_bonded_dsi)
>>>> +static unsigned long dsi_get_pclk_rate(const struct 
>>>> drm_display_mode *mode, bool is_bonded_dsi)
>>>>   {
>>>> -    struct drm_display_mode *mode = msm_host->mode;
>>>>       unsigned long pclk_rate;
>>>>       pclk_rate = mode->clock * 1000;
>>>> @@ -588,12 +587,18 @@ static unsigned long dsi_get_pclk_rate(struct 
>>>> msm_dsi_host *msm_host, bool is_bo
>>>>       return pclk_rate;
>>>>   }
>>>> -static void dsi_calc_pclk(struct msm_dsi_host *msm_host, bool 
>>>> is_bonded_dsi)
>>>> +unsigned long dsi_byte_clk_get_rate(struct mipi_dsi_host *host, 
>>>> bool is_bonded_dsi,
>>>> +        const struct drm_display_mode *mode)
>>>>   {
>>>> +    struct msm_dsi_host *msm_host = to_msm_dsi_host(host);
>>>>       u8 lanes = msm_host->lanes;
>>>>       u32 bpp = dsi_get_bpp(msm_host->format);
>>>> -    unsigned long pclk_rate = dsi_get_pclk_rate(msm_host, 
>>>> is_bonded_dsi);
>>>> -    u64 pclk_bpp = (u64)pclk_rate * bpp;
>>>> +    unsigned long pclk_rate;
>>>> +    u64 pclk_bpp;
>>>> +
>>>> +    pclk_rate = dsi_get_pclk_rate(mode, is_bonded_dsi);
>>>> +
>>>> +    pclk_bpp = (u64)pclk_rate * bpp;
>>>
>>> Any particular reason for this? The following patch would be more 
>>> obvious:
>>>
>>>  > -    unsigned long pclk_rate = dsi_get_pclk_rate(msm_host, 
>>> is_bonded_dsi);
>>>  > +    unsigned long pclk_rate = dsi_get_pclk_rate(mode, 
>>> is_bonded_dsi);
>>>  >      u64 pclk_bpp = (u64)pclk_rate * bpp;
>>>
>>>
>>>>       if (lanes == 0) {
>>>>           pr_err("%s: forcing mdss_dsi lanes to 1\n", __func__);
>>>> @@ -606,8 +611,14 @@ static void dsi_calc_pclk(struct msm_dsi_host 
>>>> *msm_host, bool is_bonded_dsi)
>>>>       else
>>>>           do_div(pclk_bpp, (8 * lanes));
>>>> -    msm_host->pixel_clk_rate = pclk_rate;
>>>> -    msm_host->byte_clk_rate = pclk_bpp;
>>>> +    return pclk_bpp;
>>>> +}
>>>> +
>>>> +static void dsi_calc_pclk(struct msm_dsi_host *msm_host, bool 
>>>> is_bonded_dsi)
>>>> +{
>>>> +    msm_host->pixel_clk_rate = dsi_get_pclk_rate(msm_host->mode, 
>>>> is_bonded_dsi);
>>>> +    msm_host->byte_clk_rate = 
>>>> dsi_byte_clk_get_rate(&msm_host->base, is_bonded_dsi,
>>>> +            msm_host->mode);
>>>>       DBG("pclk=%lu, bclk=%lu", msm_host->pixel_clk_rate,
>>>>                   msm_host->byte_clk_rate);
>>>> @@ -635,7 +646,7 @@ int dsi_calc_clk_rate_v2(struct msm_dsi_host 
>>>> *msm_host, bool is_bonded_dsi)
>>>>       dsi_calc_pclk(msm_host, is_bonded_dsi);
>>>> -    pclk_bpp = (u64)dsi_get_pclk_rate(msm_host, is_bonded_dsi) * bpp;
>>>> +    pclk_bpp = (u64)dsi_get_pclk_rate(msm_host->mode, 
>>>> is_bonded_dsi) * bpp;
>>>>       do_div(pclk_bpp, 8);
>>>>       msm_host->src_clk_rate = pclk_bpp;
>>>
>>>
>>> Following my previous feedback:
>>>
>>> I think at this moment msm_host->src_clk_rate = 
>>> msm_host->byte_clk_rate * msm_host->lanes. If so, we can drop 
>>> dsi_get_pclk_rate() call and the multiply/do_div calculation and use 
>>> the above formula instead.
>>>
>>
>>  From what I see msm_host->src_clk_rate = pixel_clk * bpp / 8;
> 
> and msm_host->byte_clk_rate = pixel_clk * bpp / (8 * nlanes);
> 
>>
>>  From where did you get the above formula?
>>
>> I just felt that by having two APIs the next patch becomes easier 
>> because I need to just invoke the API which calculates byte clk.
> 
> Yes, I see that, it looks like a correct approach. You know, let's 
> ignore the dsi_calc_clk_rate_v2() for now, it is definitely a separate 
> change.
> 
> Could you please drop the opp_table handling from patch 2/2, move 
> assignments in dsi_byte_clk_get_rate() back to the definition lines and 
> then send it as v2?
> 

Ack, will move the assignments to definition lines. Regarding the patch 
2/2, I have responded with my concerns.