On Fri, 23 Jun 2017, Bhushan Shah wrote:
> In the lm3630a_chip_init we try to write to 0x50 register, which is
> higher value then the max_register value, this resulted in regmap_write
> return -EIO.
>
> Fix this by bumping REG_MAX value to 0x50.
>
> This code was introduced with the chip revision in commit 28e64a68a2ef,
> however setting filter strength was failing silently because it used
> unsigned int for storing and comparing the return values. Bug related to
> signedness was fixed in 2a0c316bf3cc, which made it error out correctly
> instead of failing silently.
>
> I found this issue by using this driver on LGE Nexus 5 (hammerhead).
> After this commit lm3630a_chip_init succeeds instead of failing with
> -EIO.
>
> Fixes: 28e64a68a2ef ("backlight: lm3630: apply chip revision")
> Fixes: 2a0c316bf3cc ("drivers/video/backlight/lm3630a_bl.c: fix
> signedness bug in lm3630a_chip_init()")
>
> Signed-off-by: Bhushan Shah <bshah@xxxxxxx>
> Suggested-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> ---
>
> Changes since v2:
> - Include information about commits which introduced bug in commit message
> - Include information about test hardware in commit message
> - Expand define name to REG_FILTER_STRENGTH
>
> drivers/video/backlight/lm3630a_bl.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
Applied, thanks.
> diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
> index 60d6c2ac87aa..2030a6b77a09 100644
> --- a/drivers/video/backlight/lm3630a_bl.c
> +++ b/drivers/video/backlight/lm3630a_bl.c
> @@ -31,7 +31,8 @@
> #define REG_FAULT 0x0B
> #define REG_PWM_OUTLOW 0x12
> #define REG_PWM_OUTHIGH 0x13
> -#define REG_MAX 0x1F
> +#define REG_FILTER_STRENGTH 0x50
> +#define REG_MAX 0x50
>
> #define INT_DEBOUNCE_MSEC 10
> struct lm3630a_chip {
> @@ -80,7 +81,7 @@ static int lm3630a_chip_init(struct lm3630a_chip *pchip)
>
> usleep_range(1000, 2000);
> /* set Filter Strength Register */
> - rval = lm3630a_write(pchip, 0x50, 0x03);
> + rval = lm3630a_write(pchip, REG_FILTER_STRENGTH, 0x03);
> /* set Cofig. register */
> rval |= lm3630a_update(pchip, REG_CONFIG, 0x07, pdata->pwm_ctrl);
> /* set boost control */
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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