Re: [PATCH] drm/msm/dsi: simplify pixel clk rate handling

[Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>]

On 1/18/2023 5:00 AM, Dmitry Baryshkov wrote:
> Move a call to dsi_calc_pclk() out of calc_clk_rate directly towards
> msm_dsi_host_get_phy_clk_req(). It is called for both 6g and v2 hosts.
>
> Also, while we are at it, replace another dsi_get_pclk_rate() invocation
> with using the stored value at msm_host->pixel_clk_rate.
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/msm/dsi/dsi.h      |  4 ++--
>   drivers/gpu/drm/msm/dsi/dsi_cfg.h  |  2 +-
>   drivers/gpu/drm/msm/dsi/dsi_host.c | 24 ++++++++++++------------
>   3 files changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi.h b/drivers/gpu/drm/msm/dsi/dsi.h
> index bd3763a5d723..93ec54478eb6 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi.h
> +++ b/drivers/gpu/drm/msm/dsi/dsi.h
> @@ -129,8 +129,8 @@ int dsi_dma_base_get_6g(struct msm_dsi_host *msm_host, uint64_t *iova);
>   int dsi_dma_base_get_v2(struct msm_dsi_host *msm_host, uint64_t *iova);
>   int dsi_clk_init_v2(struct msm_dsi_host *msm_host);
>   int dsi_clk_init_6g_v2(struct msm_dsi_host *msm_host);
> -int dsi_calc_clk_rate_v2(struct msm_dsi_host *msm_host, bool is_bonded_dsi);
> -int dsi_calc_clk_rate_6g(struct msm_dsi_host *msm_host, bool is_bonded_dsi);
> +int dsi_calc_clk_rate_v2(struct msm_dsi_host *msm_host);
> +int dsi_calc_clk_rate_6g(struct msm_dsi_host *msm_host);
>   void msm_dsi_host_snapshot(struct msm_disp_state *disp_state, struct mipi_dsi_host *host);
>   void msm_dsi_host_test_pattern_en(struct mipi_dsi_host *host);
>   struct drm_dsc_config *msm_dsi_host_get_dsc_config(struct mipi_dsi_host *host);
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_cfg.h b/drivers/gpu/drm/msm/dsi/dsi_cfg.h
> index 44be4a88aa83..5106e66846c3 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_cfg.h
> +++ b/drivers/gpu/drm/msm/dsi/dsi_cfg.h
> @@ -51,7 +51,7 @@ struct msm_dsi_host_cfg_ops {
>   	void* (*tx_buf_get)(struct msm_dsi_host *msm_host);
>   	void (*tx_buf_put)(struct msm_dsi_host *msm_host);
>   	int (*dma_base_get)(struct msm_dsi_host *msm_host, uint64_t *iova);
> -	int (*calc_clk_rate)(struct msm_dsi_host *msm_host, bool is_bonded_dsi);
> +	int (*calc_clk_rate)(struct msm_dsi_host *msm_host);
>   };
>   
>   struct msm_dsi_cfg_handler {
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 18fa30e1e858..7d99a108bff6 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -616,28 +616,21 @@ static void dsi_calc_pclk(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>   
>   }
>   
> -int dsi_calc_clk_rate_6g(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
> +int dsi_calc_clk_rate_6g(struct msm_dsi_host *msm_host)
>   {
> -	if (!msm_host->mode) {
> -		pr_err("%s: mode not set\n", __func__);
> -		return -EINVAL;
> -	}
> -
> -	dsi_calc_pclk(msm_host, is_bonded_dsi);
>   	msm_host->esc_clk_rate = clk_get_rate(msm_host->esc_clk);
> +
>   	return 0;
>   }
>   
> -int dsi_calc_clk_rate_v2(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
> +int dsi_calc_clk_rate_v2(struct msm_dsi_host *msm_host)
>   {
>   	u32 bpp = dsi_get_bpp(msm_host->format);
>   	u64 pclk_bpp;
>   	unsigned int esc_mhz, esc_div;
>   	unsigned long byte_mhz;
>   
> -	dsi_calc_pclk(msm_host, is_bonded_dsi);
> -
> -	pclk_bpp = (u64)dsi_get_pclk_rate(msm_host->mode, is_bonded_dsi) * bpp;
> +	pclk_bpp = msm_host->pixel_clk_rate * bpp;
>   	do_div(pclk_bpp, 8);
>   	msm_host->src_clk_rate = pclk_bpp;
>   
> @@ -2292,7 +2285,14 @@ void msm_dsi_host_get_phy_clk_req(struct mipi_dsi_host *host,
>   	const struct msm_dsi_cfg_handler *cfg_hnd = msm_host->cfg_hnd;
>   	int ret;
>   
> -	ret = cfg_hnd->ops->calc_clk_rate(msm_host, is_bonded_dsi);
> +	if (!msm_host->mode) {
> +		pr_err("%s: mode not set\n", __func__);
> +		return;
> +	}
> +
> +	dsi_calc_pclk(msm_host, is_bonded_dsi);
> +
> +	ret = cfg_hnd->ops->calc_clk_rate(msm_host);

I am not too sure what we are gaining by this.

Its not that we are replacing dsi_get_pclk_rate().

We are moving the dsi_get_pclk_rate() from the calc_clk_rate() to the 
msm_dsi_host_get_phy_clk_req().

Also, with this change, dsi_calc_clk_rate_6g() looks kind of empty to 
stand on its own.

The original intention of the calc_clk_rate() op seems to be calculate 
and store all the clocks (byte, pixel and esc).

Why change that behavior by breaking it up?

>   	if (ret) {
>   		pr_err("%s: unable to calc clk rate, %d\n", __func__, ret);
>   		return;