From: Umang Jain umang.jain@ideasonboard.com
stable inclusion from linux-4.19.207 commit 4c0307b0607e5af0a5c1525085d95069770fadcd
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[ Upstream commit f809665ee75fff3f4ea8907f406a66d380aeb184 ]
The range for analog gain mentioned in the datasheet is [0, 480]. The real gain formula mentioned in the datasheet is:
Gain = 512 / (512 – X)
Hence, values larger than 511 clearly makes no sense. The gain register field is also documented to be of 9-bits in the datasheet.
Certainly, it is enough to infer that, the kernel driver currently advertises an arbitrary analog gain max. Fix it by rectifying the value as per the data sheet i.e. 480.
Signed-off-by: Umang Jain umang.jain@ideasonboard.com Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Reviewed-by: Dave Stevenson dave.stevenson@raspberrypi.com Signed-off-by: Sakari Ailus sakari.ailus@linux.intel.com Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/media/i2c/imx258.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/media/i2c/imx258.c b/drivers/media/i2c/imx258.c index 68ce633337444..85395813c0f2e 100644 --- a/drivers/media/i2c/imx258.c +++ b/drivers/media/i2c/imx258.c @@ -46,7 +46,7 @@ /* Analog gain control */ #define IMX258_REG_ANALOG_GAIN 0x0204 #define IMX258_ANA_GAIN_MIN 0 -#define IMX258_ANA_GAIN_MAX 0x1fff +#define IMX258_ANA_GAIN_MAX 480 #define IMX258_ANA_GAIN_STEP 1 #define IMX258_ANA_GAIN_DEFAULT 0x0