Re: [PATCH 1/4] drm/msm/dsi: Adjust pclk rate for compression

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On 5/3/2023 1:33 AM, Dmitry Baryshkov wrote:
On 03/05/2023 04:19, Jessica Zhang wrote:
Divide the pclk rate by the compression ratio when DSC is enabled

Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
---
  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,
+        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 we loose precision here?
Would DIV_ROUND_UP(pclk_rate * bpp, dsc->bpc * 3) be better?

Hi Dmitry,

Acked.

Thanks,

Jessica Zhang


      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;


--
With best wishes
Dmitry




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