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[86.9.19.6]) by smtp.googlemail.com with ESMTPSA id o8-v6sm2050255wro.68.2018.07.20.07.07.18 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 20 Jul 2018 07:07:18 -0700 (PDT) Subject: Re: [PATCH V4 7/8] backlight: qcom-wled: add support for short circuit handling To: Kiran Gunda , bjorn.andersson@linaro.org, jingoohan1@gmail.com, lee.jones@linaro.org, b.zolnierkie@samsung.com, dri-devel@lists.freedesktop.org, jacek.anaszewski@gmail.com, pavel@ucw.cz, robh+dt@kernel.org, mark.rutland@arm.com, linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org Cc: linux-arm-msm@vger.kernel.org References: <1531131741-19971-1-git-send-email-kgunda@codeaurora.org> <1531131741-19971-8-git-send-email-kgunda@codeaurora.org> From: Daniel Thompson Message-ID: <1a708fea-0759-fcd0-d169-a36e21c31c28@linaro.org> Date: Fri, 20 Jul 2018 15:07:17 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1531131741-19971-8-git-send-email-kgunda@codeaurora.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/07/18 11:22, Kiran Gunda wrote: > Handle the short circuit interrupt and check if the short circuit > interrupt is valid. Re-enable the module to check if it goes > away. Disable the module altogether if the short circuit event > persists. > > Signed-off-by: Kiran Gunda > Reviewed-by: Bjorn Andersson > --- > Changes from V3: > - Added Reviewed by tag. > - Addressed minor comments from Vinod > > drivers/video/backlight/qcom-wled.c | 132 ++++++++++++++++++++++++++++++++++-- > 1 file changed, 128 insertions(+), 4 deletions(-) > > diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c > index 362d254..a14f1a6 100644 > --- a/drivers/video/backlight/qcom-wled.c > +++ b/drivers/video/backlight/qcom-wled.c > @@ -10,6 +10,9 @@ > * GNU General Public License for more details. > */ > > +#include > +#include > +#include > #include > #include > #include > @@ -64,6 +67,16 @@ > #define WLED3_SINK_REG_STR_CABC(n) (0x66 + (n * 0x10)) > #define WLED3_SINK_REG_STR_CABC_MASK BIT(7) > > +/* WLED4 specific control registers */ > +#define WLED4_CTRL_REG_SHORT_PROTECT 0x5e > +#define WLED4_CTRL_REG_SHORT_EN_MASK BIT(7) > + > +#define WLED4_CTRL_REG_SEC_ACCESS 0xd0 > +#define WLED4_CTRL_REG_SEC_UNLOCK 0xa5 > + > +#define WLED4_CTRL_REG_TEST1 0xe2 > +#define WLED4_CTRL_REG_TEST1_EXT_FET_DTEST2 0x09 > + > /* WLED4 specific sink registers */ > #define WLED4_SINK_REG_CURR_SINK 0x46 > #define WLED4_SINK_REG_CURR_SINK_MASK GENMASK(7, 4) > @@ -113,17 +126,23 @@ struct wled_config { > bool cs_out_en; > bool ext_gen; > bool cabc; > + bool external_pfet; > }; > > struct wled { > const char *name; > struct device *dev; > struct regmap *regmap; > + struct mutex lock; /* Lock to avoid race from thread irq handler */ > + ktime_t last_short_event; > u16 ctrl_addr; > u16 sink_addr; > u16 max_string_count; > u32 brightness; > u32 max_brightness; > + u32 short_count; > + bool disabled_by_short; > + bool has_short_detect; > > struct wled_config cfg; > int (*wled_set_brightness)(struct wled *wled, u16 brightness); > @@ -174,6 +193,9 @@ static int wled_module_enable(struct wled *wled, int val) > { > int rc; > > + if (wled->disabled_by_short) > + return -EFAULT; EFAULT means bad address (memory fault). Perhaps EIO or maybe even something more exotic like ENXIO might be more appropriate? > + > rc = regmap_update_bits(wled->regmap, wled->ctrl_addr + > WLED_CTRL_REG_MOD_EN, > WLED_CTRL_REG_MOD_EN_MASK, > @@ -210,18 +232,19 @@ static int wled_update_status(struct backlight_device *bl) > bl->props.state & BL_CORE_FBBLANK) > brightness = 0; > > + mutex_lock(&wled->lock); > if (brightness) { > rc = wled->wled_set_brightness(wled, brightness); > if (rc < 0) { > dev_err(wled->dev, "wled failed to set brightness rc:%d\n", > rc); > - return rc; > + goto unlock_mutex; > } > > rc = wled_sync_toggle(wled); > if (rc < 0) { > dev_err(wled->dev, "wled sync failed rc:%d\n", rc); > - return rc; > + goto unlock_mutex; > } > } > > @@ -229,15 +252,61 @@ static int wled_update_status(struct backlight_device *bl) > rc = wled_module_enable(wled, !!brightness); > if (rc < 0) { > dev_err(wled->dev, "wled enable failed rc:%d\n", rc); > - return rc; > + goto unlock_mutex; > } > } > > wled->brightness = brightness; > > +unlock_mutex: > + mutex_unlock(&wled->lock); > + > return rc; > } > > +#define WLED_SHORT_DLY_MS 20 > +#define WLED_SHORT_CNT_MAX 5 > +#define WLED_SHORT_RESET_CNT_DLY_US USEC_PER_SEC > + > +static irqreturn_t wled_short_irq_handler(int irq, void *_wled) > +{ > + struct wled *wled = _wled; > + int rc; > + s64 elapsed_time; > + > + wled->short_count++; > + mutex_lock(&wled->lock); > + rc = wled_module_enable(wled, false); > + if (rc < 0) { > + dev_err(wled->dev, "wled disable failed rc:%d\n", rc); > + goto unlock_mutex; > + } > + > + elapsed_time = ktime_us_delta(ktime_get(), > + wled->last_short_event); > + if (elapsed_time > WLED_SHORT_RESET_CNT_DLY_US) > + wled->short_count = 0; Shouldn't this reset to 1 (e.g. we have just seen a short). Daniel.