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drm/msm/dsi: fix pclk rate calculation for bonded dsi

Recently, we round up new_hdisplay once at most, for bonded dsi, we
may need twice, since they are independent links, we should round up
each half separately. This also aligns with the hdisplay we program
later in dsi_timing_setup()

Example:
full_hdisplay = 1904, dsc_bpp = 8, bpc = 8
new_full_hdisplay = DIV_ROUND_UP(1904 * 8, 8 * 3) = 635

if we use half display
new_half_hdisplay = DIV_ROUND_UP(952 * 8, 8 * 3) = 318
new_full_display = 636

Fixes: 7c9e4a554d4a ("drm/msm/dsi: Reduce pclk rate for compression")
Signed-off-by: Pengyu Luo <mitltlatltl@gmail.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/709716/
Link: https://lore.kernel.org/r/20260306163255.215456-1-mitltlatltl@gmail.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

authored by

Pengyu Luo and committed by
Dmitry Baryshkov e4eb11b3 4355b13d

+23 -6
+23 -6
drivers/gpu/drm/msm/dsi/dsi_host.c
··· 584 584 * FIXME: Reconsider this if/when CMD mode handling is rewritten to use 585 585 * transfer time and data overhead as a starting point of the calculations. 586 586 */ 587 - static unsigned long dsi_adjust_pclk_for_compression(const struct drm_display_mode *mode, 588 - const struct drm_dsc_config *dsc) 587 + static unsigned long 588 + dsi_adjust_pclk_for_compression(const struct drm_display_mode *mode, 589 + const struct drm_dsc_config *dsc, 590 + bool is_bonded_dsi) 589 591 { 590 - int new_hdisplay = DIV_ROUND_UP(mode->hdisplay * drm_dsc_get_bpp_int(dsc), 591 - dsc->bits_per_component * 3); 592 + int hdisplay, new_hdisplay, new_htotal; 592 593 593 - int new_htotal = mode->htotal - mode->hdisplay + new_hdisplay; 594 + /* 595 + * For bonded DSI, split hdisplay across two links and round up each 596 + * half separately, passing the full hdisplay would only round up once. 597 + * This also aligns with the hdisplay we program later in 598 + * dsi_timing_setup() 599 + */ 600 + hdisplay = mode->hdisplay; 601 + if (is_bonded_dsi) 602 + hdisplay /= 2; 603 + 604 + new_hdisplay = DIV_ROUND_UP(hdisplay * drm_dsc_get_bpp_int(dsc), 605 + dsc->bits_per_component * 3); 606 + 607 + if (is_bonded_dsi) 608 + new_hdisplay *= 2; 609 + 610 + new_htotal = mode->htotal - mode->hdisplay + new_hdisplay; 594 611 595 612 return mult_frac(mode->clock * 1000u, new_htotal, mode->htotal); 596 613 } ··· 620 603 pclk_rate = mode->clock * 1000u; 621 604 622 605 if (dsc) 623 - pclk_rate = dsi_adjust_pclk_for_compression(mode, dsc); 606 + pclk_rate = dsi_adjust_pclk_for_compression(mode, dsc, is_bonded_dsi); 624 607 625 608 /* 626 609 * For bonded DSI mode, the current DRM mode has the complete width of the