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Date: Mon, 7 May 2018 10:21:52 -0700
From: Bjorn Andersson <bjorn.andersson@...aro.org>
To: Kiran Gunda <kgunda@...eaurora.org>
Cc: Lee Jones <lee.jones@...aro.org>,
Daniel Thompson <daniel.thompson@...aro.org>,
Jingoo Han <jingoohan1@...il.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
linux-leds@...r.kernel.org
Subject: Re: [PATCH V1 4/5] backlight: qcom-wled: Add support for OVP
interrupt handling
On Thu 03 May 02:57 PDT 2018, Kiran Gunda wrote:
> WLED peripheral has over voltage protection(OVP) circuitry and the OVP
> fault is notified through an interrupt. Though this fault condition rising
> is due to an incorrect hardware configuration is mitigated in the hardware,
> it still needs to be detected and handled. Add support for it.
>
> When WLED module is enabled, keep OVP fault interrupt disabled for 10 ms to
> account for soft start delay.
>
> Signed-off-by: Kiran Gunda <kgunda@...eaurora.org>
> ---
> drivers/video/backlight/qcom-wled.c | 118 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 116 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
> index 2cfba77..80ae084 100644
> --- a/drivers/video/backlight/qcom-wled.c
> +++ b/drivers/video/backlight/qcom-wled.c
> @@ -23,14 +23,20 @@
>
> /* From DT binding */
> #define WLED_DEFAULT_BRIGHTNESS 2048
> -
> +#define WLED_SOFT_START_DLY_US 10000
> #define WLED3_SINK_REG_BRIGHT_MAX 0xFFF
>
> /* WLED3 Control registers */
> #define WLED3_CTRL_REG_FAULT_STATUS 0x08
> +#define WLED3_CTRL_REG_ILIM_FAULT_BIT BIT(0)
> +#define WLED3_CTRL_REG_OVP_FAULT_BIT BIT(1)
> +#define WLED4_CTRL_REG_SC_FAULT_BIT BIT(2)
> +
> +#define WLED3_CTRL_REG_INT_RT_STS 0x10
>
> #define WLED3_CTRL_REG_MOD_EN 0x46
> #define WLED3_CTRL_REG_MOD_EN_MASK BIT(7)
> +#define WLED3_CTRL_REG_MOD_EN_BIT BIT(7)
"BIT(7)" is not a "bit" it's a "mask", so perhaps you could use the
define with that name...which has the same value?
>
> #define WLED3_CTRL_REG_FREQ 0x4c
> #define WLED3_CTRL_REG_FREQ_MASK GENMASK(3, 0)
> @@ -161,9 +167,12 @@ struct wled {
> u32 short_count;
> const int *version;
> int short_irq;
> + int ovp_irq;
> bool force_mod_disable;
> + bool ovp_irq_disabled;
>
> struct wled_config cfg;
> + struct delayed_work ovp_work;
> int (*wled_set_brightness)(struct wled *wled, u16 brightness);
> int (*wled_sync_toggle)(struct wled *wled);
> };
> @@ -209,6 +218,32 @@ static int wled4_set_brightness(struct wled *wled, u16 brightness)
> return 0;
> }
>
> +static void wled_ovp_work(struct work_struct *work)
> +{
> + u32 val;
> + int rc;
> +
> + struct wled *wled = container_of(work,
> + struct wled, ovp_work.work);
> +
> + rc = regmap_read(wled->regmap, wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN,
> + &val);
> + if (rc < 0)
> + return;
> +
> + if (val & WLED3_CTRL_REG_MOD_EN_BIT) {
> + if (wled->ovp_irq > 0 && wled->ovp_irq_disabled) {
> + enable_irq(wled->ovp_irq);
> + wled->ovp_irq_disabled = false;
> + }
> + } else {
> + if (wled->ovp_irq > 0 && !wled->ovp_irq_disabled) {
> + disable_irq(wled->ovp_irq);
> + wled->ovp_irq_disabled = true;
> + }
> + }
> +}
> +
> static int wled_module_enable(struct wled *wled, int val)
> {
> int rc;
> @@ -220,7 +255,12 @@ static int wled_module_enable(struct wled *wled, int val)
> WLED3_CTRL_REG_MOD_EN,
> WLED3_CTRL_REG_MOD_EN_MASK,
> WLED3_CTRL_REG_MOD_EN_MASK);
> - return rc;
> + if (rc < 0)
> + return rc;
> +
> + schedule_delayed_work(&wled->ovp_work, WLED_SOFT_START_DLY_US);
Do you really want to delay the work on disable?
Wouldn't it be better to use a delay worker for the enablement and in
the disable case you cancel the work and just disable_irq() directly
here.
But more importantly, if this is only related to auto detection, do you
really want to enable/disable the ovp_irq after you have detected the
string configuration?
> +
> + return 0;
> }
>
> static int wled3_sync_toggle(struct wled *wled)
> @@ -346,6 +386,36 @@ static irqreturn_t wled_short_irq_handler(int irq, void *_wled)
> return IRQ_HANDLED;
> }
>
> +static irqreturn_t wled_ovp_irq_handler(int irq, void *_wled)
> +{
> + struct wled *wled = _wled;
> + int rc;
> + u32 int_sts, fault_sts;
> +
> + rc = regmap_read(wled->regmap,
> + wled->ctrl_addr + WLED3_CTRL_REG_INT_RT_STS, &int_sts);
> + if (rc < 0) {
> + dev_err(wled->dev, "Error in reading WLED3_INT_RT_STS rc=%d\n",
> + rc);
> + return IRQ_HANDLED;
> + }
> +
> + rc = regmap_read(wled->regmap, wled->ctrl_addr +
> + WLED3_CTRL_REG_FAULT_STATUS, &fault_sts);
> + if (rc < 0) {
> + dev_err(wled->dev, "Error in reading WLED_FAULT_STATUS rc=%d\n",
> + rc);
> + return IRQ_HANDLED;
> + }
> +
> + if (fault_sts &
> + (WLED3_CTRL_REG_OVP_FAULT_BIT | WLED3_CTRL_REG_ILIM_FAULT_BIT))
> + dev_dbg(wled->dev, "WLED OVP fault detected, int_sts=%x fault_sts= %x\n",
> + int_sts, fault_sts);
> +
It's hard to give a good review on this, as the actual logic comes in
the next patch. And as these two patches both implement auto detection
(without a clear separation) I think you should squash them.
> + return IRQ_HANDLED;
> +}
> +
> static int wled3_setup(struct wled *wled)
> {
> u16 addr;
> @@ -821,6 +891,44 @@ static int wled_configure_short_irq(struct wled *wled,
> return rc;
> }
>
> +static int wled_configure_ovp_irq(struct wled *wled,
> + struct platform_device *pdev)
> +{
> + int rc = 0;
> + u32 val;
> +
> + if (*wled->version == WLED_PM8941)
> + return 0;
> +
> + wled->ovp_irq = platform_get_irq_byname(pdev, "ovp");
> + if (wled->ovp_irq < 0) {
> + dev_dbg(&pdev->dev, "ovp irq is not used\n");
> + return 0;
> + }
> +
> + rc = devm_request_threaded_irq(wled->dev, wled->ovp_irq, NULL,
> + wled_ovp_irq_handler, IRQF_ONESHOT,
> + "wled_ovp_irq", wled);
> + if (rc < 0) {
> + dev_err(wled->dev, "Unable to request ovp_irq (err:%d)\n",
> + rc);
wled->ovp_irq might be > 0 here which means wled_ovp_work() will find it
valid and call enabled_irq()/disable_irq() on it.
> + return 0;
> + }
> +
Regards,
Bjorn
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