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Date: Thu, 17 Oct 2019 12:09:45 +0100
From: Daniel Thompson <daniel.thompson@...aro.org>
To: Kiran Gunda <kgunda@...eaurora.org>
Cc: bjorn.andersson@...aro.org, jingoohan1@...il.com,
lee.jones@...aro.org, b.zolnierkie@...sung.com,
dri-devel@...ts.freedesktop.org, jacek.anaszewski@...il.com,
pavel@....cz, robh+dt@...nel.org, mark.rutland@....com,
linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, Andy Gross <agross@...nel.org>,
linux-arm-msm@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH V7 5/6] backlight: qcom-wled: add support for short
circuit handling.
On Wed, Oct 16, 2019 at 03:43:45PM +0530, 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 <kgunda@...eaurora.org>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>
> ---
> 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 2807b4b..b5b125c 100644
> --- a/drivers/video/backlight/qcom-wled.c
> +++ b/drivers/video/backlight/qcom-wled.c
> @@ -2,6 +2,9 @@
> /* Copyright (c) 2015, Sony Mobile Communications, AB.
> */
>
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/ktime.h>
> #include <linux/kernel.h>
> #include <linux/backlight.h>
> #include <linux/module.h>
> @@ -56,6 +59,16 @@
> #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)
> @@ -105,17 +118,23 @@ 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);
> @@ -166,6 +185,9 @@ static int wled_module_enable(struct wled *wled, int val)
> {
> int rc;
>
> + if (wled->disabled_by_short)
> + return -ENXIO;
> +
> rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
> WLED3_CTRL_REG_MOD_EN,
> WLED3_CTRL_REG_MOD_EN_MASK,
> @@ -202,18 +224,19 @@ 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;
> }
> }
>
> @@ -221,15 +244,61 @@ 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 = 1;
> +
> + if (wled->short_count > WLED_SHORT_CNT_MAX) {
> + dev_err(wled->dev, "Short trigged %d times, disabling WLED forever!\n",
> + wled->short_count);
> + wled->disabled_by_short = true;
> + goto unlock_mutex;
> + }
> +
> + wled->last_short_event = ktime_get();
> +
> + msleep(WLED_SHORT_DLY_MS);
> + rc = wled_module_enable(wled, true);
> + if (rc < 0)
> + dev_err(wled->dev, "wled enable failed rc:%d\n", rc);
> +
> +unlock_mutex:
> + mutex_unlock(&wled->lock);
> +
> + return IRQ_HANDLED;
> +}
> +
> static int wled3_setup(struct wled *wled)
> {
> u16 addr;
> @@ -318,7 +387,7 @@ static int wled4_setup(struct wled *wled)
> int rc, temp, i, j;
> u16 addr;
> u8 sink_en = 0;
> - u32 sink_cfg = 0;
> + u32 sink_cfg;
>
> rc = regmap_update_bits(wled->regmap,
> wled->ctrl_addr + WLED3_CTRL_REG_OVP,
> @@ -340,6 +409,21 @@ static int wled4_setup(struct wled *wled)
> if (rc < 0)
> return rc;
>
> + if (wled->cfg.external_pfet) {
> + /* Unlock the secure register access */
> + rc = regmap_write(wled->regmap, wled->ctrl_addr +
> + WLED4_CTRL_REG_SEC_ACCESS,
> + WLED4_CTRL_REG_SEC_UNLOCK);
> + if (rc < 0)
> + return rc;
> +
> + rc = regmap_write(wled->regmap,
> + wled->ctrl_addr + WLED4_CTRL_REG_TEST1,
> + WLED4_CTRL_REG_TEST1_EXT_FET_DTEST2);
> + if (rc < 0)
> + return rc;
> + }
> +
> rc = regmap_read(wled->regmap, wled->sink_addr +
> WLED4_SINK_REG_CURR_SINK, &sink_cfg);
> if (rc < 0)
> @@ -425,6 +509,7 @@ static int wled4_setup(struct wled *wled)
> .num_strings = 4,
> .switch_freq = 11,
> .cabc = false,
> + .external_pfet = false,
> };
>
> static const u32 wled3_boost_i_limit_values[] = {
> @@ -590,6 +675,7 @@ static int wled_configure(struct wled *wled, int version)
> { "qcom,cs-out", &cfg->cs_out_en, },
> { "qcom,ext-gen", &cfg->ext_gen, },
> { "qcom,cabc", &cfg->cabc, },
> + { "qcom,external-pfet", &cfg->external_pfet, },
> };
>
> prop_addr = of_get_address(dev->of_node, 0, NULL, NULL);
> @@ -678,6 +764,38 @@ static int wled_configure(struct wled *wled, int version)
> return 0;
> }
>
> +static int wled_configure_short_irq(struct wled *wled,
> + struct platform_device *pdev)
> +{
> + int rc, short_irq;
> +
> + if (!wled->has_short_detect)
> + return 0;
> +
> + rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
> + WLED4_CTRL_REG_SHORT_PROTECT,
> + WLED4_CTRL_REG_SHORT_EN_MASK,
> + WLED4_CTRL_REG_SHORT_EN_MASK);
> + if (rc < 0)
> + return rc;
> +
> + short_irq = platform_get_irq_byname(pdev, "short");
> + if (short_irq < 0) {
> + dev_dbg(&pdev->dev, "short irq is not used\n");
> + return 0;
> + }
> +
> + rc = devm_request_threaded_irq(wled->dev, short_irq,
> + NULL, wled_short_irq_handler,
> + IRQF_ONESHOT,
> + "wled_short_irq", wled);
> + if (rc < 0)
> + dev_err(wled->dev, "Unable to request short_irq (err:%d)\n",
> + rc);
> +
> + return rc;
> +}
> +
> static const struct backlight_ops wled_ops = {
> .update_status = wled_update_status,
> };
> @@ -711,6 +829,7 @@ static int wled_probe(struct platform_device *pdev)
> return -ENODEV;
> }
>
> + mutex_init(&wled->lock);
> rc = wled_configure(wled, version);
> if (rc)
> return rc;
> @@ -725,6 +844,7 @@ static int wled_probe(struct platform_device *pdev)
> break;
>
> case 4:
> + wled->has_short_detect = true;
> rc = wled4_setup(wled);
> if (rc) {
> dev_err(&pdev->dev, "wled4_setup failed\n");
> @@ -737,6 +857,10 @@ static int wled_probe(struct platform_device *pdev)
> break;
> }
>
> + rc = wled_configure_short_irq(wled, pdev);
> + if (rc < 0)
> + return rc;
> +
> val = WLED_DEFAULT_BRIGHTNESS;
> of_property_read_u32(pdev->dev.of_node, "default-brightness", &val);
>
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
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