linux-kernel - Re: [PATCH] leds: mt6360: Fix the second LED can not enable torch mode by V4L2

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Message-ID: <20240411065511.GB6194@google.com>
Date: Thu, 11 Apr 2024 07:55:11 +0100
From: Lee Jones <lee@...nel.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: ChiaEn Wu <chiaen_wu@...htek.com>, pavel@....cz, matthias.bgg@...il.com,
	linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, peterwu.pub@...il.com,
	cy_huang@...htek.com
Subject: Re: [PATCH] leds: mt6360: Fix the second LED can not enable torch
 mode by V4L2

On Tue, 09 Apr 2024, AngeloGioacchino Del Regno wrote:

Not sure why, but this mail was sent unthreaded from the original.

> Il 09/04/24 12:21, ChiaEn Wu ha scritto:
> > V4L2 will disable strobe mode of the LED device when enable torch mode,
> > but this logic will conflict with the "priv->fled_torch_used"
> > in "mt6360_strobe_set()". So after enabling torch mode of the first
> > LED, the second LED will not be able to enable torch mode correctly.
> > 
> > Therefore, at the beginning of "mt6360_strobe_set()", check whether the
> > state of the upcoming change and the current LED device state are the
> > same, so as to avoid the above problem.
> > 
> > Signed-off-by: ChiaEn Wu <chiaen_wu@...htek.com>
> > ---
> >   drivers/leds/flash/leds-mt6360.c | 12 +++++++++++-
> >   1 file changed, 11 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/leds/flash/leds-mt6360.c b/drivers/leds/flash/leds-mt6360.c
> > index a90de82f4568..1b75b4d36834 100644
> > --- a/drivers/leds/flash/leds-mt6360.c
> > +++ b/drivers/leds/flash/leds-mt6360.c
> > @@ -241,10 +241,20 @@ static int mt6360_strobe_set(struct led_classdev_flash *fl_cdev, bool state)
> >   	u32 enable_mask = MT6360_STROBEN_MASK | MT6360_FLCSEN_MASK(led->led_no);
> >   	u32 val = state ? MT6360_FLCSEN_MASK(led->led_no) : 0;
> >   	u32 prev = priv->fled_strobe_used, curr;
> > -	int ret;
> > +	int ret = 0;
> 
> I prefer that you leave ret uninitialized here, and...

What's the reason for this?

> >   	mutex_lock(&priv->lock);
> > +	/*
> > +	 * If the state of the upcoming change is the same as the current LED
> > +	 * device state, then skip the subsequent code to avoid conflict
> > +	 * with the flow of turning on LED torch mode in V4L2.
> > +	 */
> > +	if (state == !!(BIT(led->led_no) & prev)) {
> > +		dev_info(lcdev->dev, "No change in strobe state [0x%x]\n", prev);
> 
> ...that you do here, instead
> 
> 		ret = 0;
> 		goto unlock;
> 
> With that addressed,
> 
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...laobra.com>
> 
> 

-- 
Lee Jones [李琼斯]