From: Manikandan Muralidharan <manikandan.m@microchip•com>
To: <maarten.lankhorst@linux•intel.com>, <mripard@kernel•org>,
<tzimmermann@suse•de>, <airlied@gmail•com>, <simona@ffwll•ch>,
<nicolas.ferre@microchip•com>, <alexandre.belloni@bootlin•com>,
<claudiu.beznea@tuxon•dev>, <lee@kernel•org>,
<dri-devel@lists•freedesktop.org>,
<linux-arm-kernel@lists•infradead.org>,
<linux-kernel@vger•kernel.org>
Cc: <manikandan.m@microchip•com>
Subject: [PATCH 3/8] drm: atmel-hlcdc: simplify clock divider selection with DIV_ROUND_CLOSEST
Date: Tue, 19 May 2026 14:31:30 +0530 [thread overview]
Message-ID: <20260519090135.1188405-4-manikandan.m@microchip.com> (raw)
In-Reply-To: <20260519090135.1188405-1-manikandan.m@microchip.com>
DIV_ROUND_CLOSEST naturally selects the nearest divider, making the
manual 10x proximity check redundant. Drop it and switch from
DIV_ROUND_UP accordingly.
Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip•com>
---
drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 16 ++--------------
1 file changed, 2 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index 9673fbce42a7..f30138da1ed8 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -112,28 +112,16 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
mask |= ATMEL_HLCDC_CLKSEL;
}
- div = DIV_ROUND_UP(prate, mode_rate);
+ div = DIV_ROUND_CLOSEST(prate, mode_rate);
if (div < 2) {
div = 2;
} else if (ATMEL_HLCDC_CLKDIV(div) & ~ATMEL_HLCDC_CLKDIV_MASK) {
/* The divider ended up too big, try a lower base rate. */
cfg &= ~ATMEL_HLCDC_CLKSEL;
prate /= 2;
- div = DIV_ROUND_UP(prate, mode_rate);
+ div = DIV_ROUND_CLOSEST(prate, mode_rate);
if (ATMEL_HLCDC_CLKDIV(div) & ~ATMEL_HLCDC_CLKDIV_MASK)
div = ATMEL_HLCDC_CLKDIV_MASK;
- } else {
- int div_low = prate / mode_rate;
-
- if (div_low >= 2 &&
- (10 * (prate / div_low - mode_rate) <
- (mode_rate - prate / div)))
- /*
- * At least 10 times better when using a higher
- * frequency than requested, instead of a lower.
- * So, go with that.
- */
- div = div_low;
}
cfg |= ATMEL_HLCDC_CLKDIV(div);
--
2.25.1
next prev parent reply other threads:[~2026-05-19 9:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-19 9:01 [PATCH 0/8] drm: atmel-hlcdc: fix clock handling and add LVDS support Manikandan Muralidharan
2026-05-19 9:01 ` [PATCH 1/8] drm: atmel-hlcdc: Fix off-by-one in vertical back porch setting Manikandan Muralidharan
2026-05-19 9:01 ` [PATCH 2/8] drm: atmel-hlcdc: reorder timing register writes after clock setup Manikandan Muralidharan
2026-05-19 9:01 ` Manikandan Muralidharan [this message]
2026-05-19 9:01 ` [PATCH 4/8] drm: atmel-hlcdc: define ATMEL_HLCDC_CLKDIV_MAX and fix divider fallback Manikandan Muralidharan
2026-05-19 9:01 ` [PATCH 5/8] drm: atmel-hlcdc: extract clock setup into a dedicated helper Manikandan Muralidharan
2026-05-19 9:01 ` [PATCH 6/8] drm: atmel-hlcdc: add XLCDC clock bypass support for small dividers Manikandan Muralidharan
2026-05-27 14:55 ` Lee Jones
2026-05-19 9:01 ` [PATCH 7/8] drm: atmel-hlcdc: add and configure LVDS PLL clock support Manikandan Muralidharan
2026-05-19 9:01 ` [PATCH 8/8] drm: atmel-hlcdc: add LVDS output mode support Manikandan Muralidharan
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