From 6acb691824933535219dfd94d9d97c922f5593d2 Mon Sep 17 00:00:00 2001 From: Michael Tretter Date: Fri, 6 Oct 2023 17:07:07 +0200 Subject: [PATCH] drm/bridge: samsung-dsim: calculate porches in Hz Calculating the byte_clk in kHz is imprecise for a hs_clock of 55687500 Hz, which may be used with a pixel clock of 74.25 MHz with mode 1920x1080-30. Fix the calculation by using HZ instead of kHZ. This requires to change the type to u64 to prevent overflows of the integer type. Reviewed-by: Adam Ford #imx8mm-beacon Tested-by: Adam Ford #imx8mm-beacon Tested-by: Frieder Schrempf # Kontron BL i.MX8MM + Waveshare 10.1inch HDMI LCD (E) Reviewed-by: Marco Felsch Signed-off-by: Michael Tretter Tested-by: Marek Szyprowski Link: https://lore.kernel.org/r/20230818-samsung-dsim-v2-5-846603df0e0a@pengutronix.de Signed-off-by: Neil Armstrong Link: https://patchwork.freedesktop.org/patch/msgid/20230818-samsung-dsim-v2-5-846603df0e0a@pengutronix.de --- drivers/gpu/drm/bridge/samsung-dsim.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c index a0310f050693..3a5c7618e7aa 100644 --- a/drivers/gpu/drm/bridge/samsung-dsim.c +++ b/drivers/gpu/drm/bridge/samsung-dsim.c @@ -988,10 +988,12 @@ static void samsung_dsim_set_display_mode(struct samsung_dsim *dsi) u32 reg; if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO) { - int byte_clk_khz = dsi->hs_clock / 1000 / 8; - int hfp = DIV_ROUND_UP((m->hsync_start - m->hdisplay) * byte_clk_khz, m->clock); - int hbp = DIV_ROUND_UP((m->htotal - m->hsync_end) * byte_clk_khz, m->clock); - int hsa = DIV_ROUND_UP((m->hsync_end - m->hsync_start) * byte_clk_khz, m->clock); + u64 byte_clk = dsi->hs_clock / 8; + u64 pix_clk = m->clock * 1000; + + int hfp = DIV64_U64_ROUND_UP((m->hsync_start - m->hdisplay) * byte_clk, pix_clk); + int hbp = DIV64_U64_ROUND_UP((m->htotal - m->hsync_end) * byte_clk, pix_clk); + int hsa = DIV64_U64_ROUND_UP((m->hsync_end - m->hsync_start) * byte_clk, pix_clk); /* remove packet overhead when possible */ hfp = max(hfp - 6, 0);