Title suggestion: use the wording "reduce pclk rate" :)
(Eventually "when DSC is enabled", instead of "for compression")
On 2023-05-02 18:19:12, Jessica Zhang wrote:
> Divide the pclk rate by the compression ratio when DSC is enabled
>
> Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
Thank you so much for sending this. The compression ratio was applied
to hdisplay, but not the clocks yet, and with this patch I get a massive
reduction in clock speeds on the Xperia XZ3, without regressions nor
affecting performance/fps:
gcc_sys_noc_cpuss_ahb_clk 1 1 0 19200000 0 0 50000 Y
gcc_cpuss_ahb_clk 1 1 0 19200000 0 0 50000 Y
bi_tcxo 6 6 0 19200000 0 0 50000 Y
dsi0vco_clk 1 1 0 [-1873793994-]{+1249195898+} 0 0 50000 Y
dsi0_pll_out_div_clk 1 1 0 [-1873793994-]{+624597949+} 0 0 50000 Y
dsi0_pll_post_out_div_clk 0 0 0 [-468448498-]{+156149487+} 0 0 50000 Y
dsi0_pll_bit_clk 2 2 0 [-1873793994-]{+624597949+} 0 0 50000 Y
dsi0_pclk_mux 1 1 0 [-1873793994-]{+624597949+} 0 0 50000 Y
dsi0_phy_pll_out_dsiclk 1 1 0 [-312298999-]{+104099659+} 0 0 50000 Y
disp_cc_mdss_pclk0_clk_src 1 1 0 [-312298999-]{+104099659+} 0 0 50000 Y
disp_cc_mdss_pclk0_clk 1 1 0 [-312298999-]{+104099659+} 0 0 50000 Y
dsi0_pll_by_2_bit_clk 0 0 0 [-936896997-]{+312298974+} 0 0 50000 Y
dsi0_phy_pll_out_byteclk 1 1 0 [-234224249-]{+78074743+} 0 0 50000 Y
disp_cc_mdss_byte0_clk_src 2 2 0 [-234224249-]{+78074743+} 0 0 50000 Y
disp_cc_mdss_byte0_div_clk_src 1 1 0 [-117112125-]{+39037372+} 0 0 50000 Y
disp_cc_mdss_byte0_intf_clk 1 1 0 [-117112125-]{+39037372+} 0 0 50000 Y
disp_cc_mdss_byte0_clk 1 1 0 [-234224249-]{+78074743+} 0 0 50000 Y
gpu_cc_pll1 0 0 0 500000097 0 0 50000 N
disp_cc_mdss_dp_pixel_clk_src 0 0 0 19200000 0 0 50000 N
disp_cc_mdss_dp_pixel_clk 0 0 0 19200000 0 0 50000 N
Reviewed-by: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/msm/dsi/dsi_host.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 43a5ec33eee8..35c69dbe5f6f 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -561,7 +561,8 @@ 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(const struct drm_display_mode *mode, bool is_bonded_dsi)
> +static unsigned long dsi_get_pclk_rate(const struct drm_display_mode *mode,
It is a bit unfortunate that this function is called so often with the
same parameters, doing the same calculation over and over.
> + struct drm_dsc_config *dsc, bool is_bonded_dsi)
> {
> unsigned long pclk_rate;
>
> @@ -576,6 +577,11 @@ static unsigned long dsi_get_pclk_rate(const struct drm_display_mode *mode, bool
> if (is_bonded_dsi)
> pclk_rate /= 2;
>
> + /* If DSC is enabled, divide pclk by compression ratio */
> + if (dsc)
> + pclk_rate = DIV_ROUND_UP(pclk_rate,
> + dsc->bits_per_component * 3 / msm_dsc_get_bpp_int(dsc));
Don't forget to mention that this series depends on the DSC helpers. I
don't think the linked DSC 1.2 series depends on it (at least it doesn't
mention it):
https://lore.kernel.org/linux-arm-msm/20230329-rfc-msm-dsc-helper-v6-2-cb7f59f0f7fb@xxxxxxxxxxx/
- Marijn
> +
> return pclk_rate;
> }
>
> @@ -585,7 +591,7 @@ unsigned long dsi_byte_clk_get_rate(struct mipi_dsi_host *host, bool is_bonded_d
> 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(mode, is_bonded_dsi);
> + unsigned long pclk_rate = dsi_get_pclk_rate(mode, msm_host->dsc, is_bonded_dsi);
> u64 pclk_bpp = (u64)pclk_rate * bpp;
>
> if (lanes == 0) {
> @@ -604,7 +610,7 @@ unsigned long dsi_byte_clk_get_rate(struct mipi_dsi_host *host, bool is_bonded_d
>
> 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->pixel_clk_rate = dsi_get_pclk_rate(msm_host->mode, msm_host->dsc, is_bonded_dsi);
> msm_host->byte_clk_rate = dsi_byte_clk_get_rate(&msm_host->base, is_bonded_dsi,
> msm_host->mode);
>
> @@ -634,7 +640,7 @@ 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->mode, is_bonded_dsi) * bpp;
> + pclk_bpp = (u64)dsi_get_pclk_rate(msm_host->mode, msm_host->dsc, is_bonded_dsi) * bpp;
> do_div(pclk_bpp, 8);
> msm_host->src_clk_rate = pclk_bpp;
>
>
> --
> 2.40.1
>
