From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Leitner Date: Tue, 10 Nov 2026 14:10:11 +0100 Subject: [PATCH v3 2/8] media: i2c: ov9282: fix pixel rate and line time calculation MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20261110-ov9282-fixes-v3-2-cb6df80cbc22@linux.dev> References: <20261110-ov9282-fixes-v3-0-cb6df80cbc22@linux.dev> In-Reply-To: <20261110-ov9282-fixes-v3-0-cb6df80cbc22@linux.dev> To: Sakari Ailus , Dave Stevenson , Mauro Carvalho Chehab , Daniele Alessandrelli , "Paul J. Murphy" , Martina Krasteva , Richard Leitner , Hans Verkuil , Bryan O'Donoghue , Jacopo Mondi Cc: Mauro Carvalho Chehab , Gyula Kelemen , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1794316220; l=4128; i=richard.leitner@linux.dev; s=20250225; h=from:subject:message-id; bh=vEUkcmhrgbccMnrDYbK6Bg1byQZHGlfGlZNdCKAMiuU=; b=mEqQuSHLSwfITSoGjXfDyvKub52W7OZOymcD+YY09BUBQkTWVW01eU4cOX0ErxhtOY+8AXVHQ cSx2x3kBY2zD2N3Zrmda0yGMKy20sl4bqgqg9rMicZnP7GSLjf/Wdt4 X-Developer-Key: i=richard.leitner@linux.dev; a=ed25519; pk=8hZNyyyQFqZ5ruVJsSGBSPIrmJpfDm5HwHU4QVOP1Pk= X-Endpoint-Received: by B4 Relay for richard.leitner@linux.dev/20250225 with auth_id=350 List-Id: B4 Relay Submissions The OV9282_PIXEL_RATE_8BIT is calculated incorrectly from the OV9282_LINK_FREQ. The hardware scales the pixel rate by changing the multiplier from 0x50 (for 10 bit) to 0x60 (for 8 bit). Resulting in a x1.2 factor. The current OV9282_PIXEL_RATE_8BIT calculation scales from /10 (for 10 bit) to /8 (for 8 bit). This results in a x1.25 factor. As all the inputs to the pixel rate calculation are constant in this driver also define the OV9282_PIXEL_RATE_{8,10}BIT as constants. Additionally introduce a new function to calculate the current line time in nanoseconds and use it in ov9282_exposure_to_us(). Kudos to Dave Stevenson for pointing me into the right direction! Link: https://lore.kernel.org/linux-media/CAPY8ntBaSHjztuSLTOtv9KYvEbmcbinSMJ78ZDg+0sZg-1fz3Q@mail.gmail.com/ Fixes: df60764ea5210 ("media: i2c: ov9282: dynamic flash_duration maximum") Fixes: 43ac0cac18f41 ("media: i2c: ov9282: Add support for 8bit readout") Cc: stable@vger.kernel.org Reviewed-by: Dave Stevenson Signed-off-by: Richard Leitner --- drivers/media/i2c/ov9282.c | 50 +++++++++++++++++++++++++++++++++------------- 1 file changed, 36 insertions(+), 14 deletions(-) diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c index 546b43c209097..d60396e46ab0f 100644 --- a/drivers/media/i2c/ov9282.c +++ b/drivers/media/i2c/ov9282.c @@ -10,10 +10,12 @@ #include #include #include +#include #include #include #include #include +#include #include #include @@ -111,11 +113,14 @@ #define OV9282_LINK_FREQ 400000000 #define OV9282_NUM_DATA_LANES 2 -/* Pixel rate */ -#define OV9282_PIXEL_RATE_10BIT (OV9282_LINK_FREQ * 2 * \ - OV9282_NUM_DATA_LANES / 10) -#define OV9282_PIXEL_RATE_8BIT (OV9282_LINK_FREQ * 2 * \ - OV9282_NUM_DATA_LANES / 8) +/* + * Pixel rate: Derived from the PLL2 clock tree. + * For 10 bit it's exactly the same as the sample PLL configuration. + * For 8 bit the PLL2 multiplier (REG_PLL_CTRL_0D) is changed 0x50 -> 0x60, + * which results in x1.2 and therefore 160 MHz x 1.2 = 192 MHz. + */ +#define OV9282_PIXEL_RATE_10BIT 160000000 +#define OV9282_PIXEL_RATE_8BIT 192000000 /* * OV9282 native and active pixel array size. @@ -472,6 +477,32 @@ static inline struct ov9282 *to_ov9282(struct v4l2_subdev *subdev) return container_of(subdev, struct ov9282, sd); } +/** + * ov9282_line_time_ns() - Calculate duration of one sensor line. + * @ov9282: pointer to ov9282 device + * + * Return: line time in nanoseconds. + */ +static u32 ov9282_line_time_ns(struct ov9282 *ov9282) +{ + u64 hts = ov9282->cur_mode->width + ov9282->hblank_ctrl->val; + + return div_u64(hts * NSEC_PER_SEC, *ov9282->pixel_rate->p_cur.p_s64); +} + +/** + * ov9282_exposure_to_us() - Convert an exposure register value to microseconds + * @ov9282: pointer to ov9282 device + * @exposure: exposure register value to convert + * + * Return: microsecond representation of the given exposure register value. + */ +static u32 ov9282_exposure_to_us(struct ov9282 *ov9282, u32 exposure) +{ + return div_u64((u64)exposure * ov9282_line_time_ns(ov9282), + NSEC_PER_USEC); +} + /** * ov9282_update_controls() - Update control ranges based on streaming mode * @ov9282: pointer to ov9282 device @@ -510,15 +541,6 @@ static int ov9282_update_controls(struct ov9282 *ov9282, mode->vblank_max, 1, mode->vblank); } -static u32 ov9282_exposure_to_us(struct ov9282 *ov9282, u32 exposure) -{ - /* calculate exposure time in µs */ - u32 frame_width = ov9282->cur_mode->width + ov9282->hblank_ctrl->val; - u32 trow_us = frame_width / (ov9282->pixel_rate->val / 1000000UL); - - return exposure * trow_us; -} - /** * ov9282_update_exp_gain() - Set updated exposure and gain * @ov9282: pointer to ov9282 device -- 2.53.0