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| author | Luca Ceresoli <luca.ceresoli@bootlin.com> | 2026-02-26 19:16:44 +0300 |
|---|---|---|
| committer | Luca Ceresoli <luca.ceresoli@bootlin.com> | 2026-03-10 00:32:05 +0300 |
| commit | 2f22702dc0fee06a240404e0f7ead5b789b253d8 (patch) | |
| tree | 8b24f440e98433e37fdf78753ffaf895cb727e3c | |
| parent | 7149be786da012afc6bae293d38f8c1fff1fb90d (diff) | |
| download | linux-2f22702dc0fee06a240404e0f7ead5b789b253d8.tar.xz | |
drm/bridge: ti-sn65dsi83: fix CHA_DSI_CLK_RANGE rounding
The DSI frequency must be in the range:
(CHA_DSI_CLK_RANGE * 5 MHz) <= DSI freq < ((CHA_DSI_CLK_RANGE + 1) * 5 MHz)
So the register value should point to the lower range value, but
DIV_ROUND_UP() rounds the division to the higher range value, resulting in
an excess of 1 (unless the frequency is an exact multiple of 5 MHz).
For example for a 437100000 MHz clock CHA_DSI_CLK_RANGE should be 87 (0x57):
(87 * 5 = 435) <= 437.1 < (88 * 5 = 440)
but current code returns 88 (0x58).
Fix the computation by removing the DIV_ROUND_UP().
Fixes: ceb515ba29ba ("drm/bridge: ti-sn65dsi83: Add TI SN65DSI83 and SN65DSI84 driver")
Cc: stable@vger.kernel.org
Reviewed-by: Marek Vasut <marek.vasut@mailbox.org>
Link: https://patch.msgid.link/20260226-ti-sn65dsi83-dual-lvds-fixes-and-test-pattern-v1-1-2e15f5a9a6a0@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
| -rw-r--r-- | drivers/gpu/drm/bridge/ti-sn65dsi83.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c index f6736b4457bb..d2a81175d279 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c @@ -351,9 +351,9 @@ static u8 sn65dsi83_get_dsi_range(struct sn65dsi83 *ctx, * DSI_CLK = mode clock * bpp / dsi_data_lanes / 2 * the 2 is there because the bus is DDR. */ - return DIV_ROUND_UP(clamp((unsigned int)mode->clock * - mipi_dsi_pixel_format_to_bpp(ctx->dsi->format) / - ctx->dsi->lanes / 2, 40000U, 500000U), 5000U); + return clamp((unsigned int)mode->clock * + mipi_dsi_pixel_format_to_bpp(ctx->dsi->format) / + ctx->dsi->lanes / 2, 40000U, 500000U) / 5000U; } static u8 sn65dsi83_get_dsi_div(struct sn65dsi83 *ctx) |