[EXT] Re: [PATCH 2/5] i2c: imx-lpi2c: add IRQF_NO_SUSPEND IRQ flag

[Carlos Song]

> -----Original Message-----
> From: Stefan Wahren <wahrenst at gmx.net>
> Sent: Thursday, August 29, 2024 6:53 PM
> To: Carlos Song <carlos.song at nxp.com>; Aisheng Dong
> <aisheng.dong at nxp.com>; andi.shyti at kernel.org; shawnguo at kernel.org;
> s.hauer at pengutronix.de; kernel at pengutronix.de; festevam at gmail.com
> Cc: linux-i2c at vger.kernel.org; imx at lists.linux.dev;
> linux-arm-kernel at lists.infradead.org; linux-kernel at vger.kernel.org
> Subject: [EXT] Re: [PATCH 2/5] i2c: imx-lpi2c: add IRQF_NO_SUSPEND IRQ flag
> 
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> 
> Hi Carlos,
> 
> Am 29.08.24 um 11:37 schrieb carlos.song at nxp.com:
> > From: Carlos Song <carlos.song at nxp.com>
> >
> > Set IRQF_NO_SUSPEND flag when request_irq(). Some devices such as
> > extend GPIO will need i2c transfer during the entire system suspend
> > and resume period so keep it enabled.
> do you mean GPIO expander which are connected to I2C?
> 
> Do the mentioned expander have a dedicated IRQ line or does the host needs to
> poll I2C?
> 
Hi,

Yes, we have both gpio expanders. But devices polling i2c may have a stronger need for this.
Like pmic, it may use i2c transfer at any time regardless of whether the system enters suspend or disables irq.
This flag is added to make the I2c irq won't be mask in the system suspend.

But I find that it is not enough if just add this flag. Because lpi2c clock is enabled at rpm function. If rpm is disabled,
the lpi2c still can not work. So I will add an extra patch to make lpi2c can work also at no irq stage. I will send this patch
with this in next new patch serials.

> Best regards
> 
> >
> > Signed-off-by: Carlos Song <carlos.song at nxp.com>
> > Signed-off-by: Frank Li <Frank.Li at nxp.com>
> > ---
> >   drivers/i2c/busses/i2c-imx-lpi2c.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c
> > b/drivers/i2c/busses/i2c-imx-lpi2c.c
> > index c8f3dadfb36e..23f83f10d5f6 100644
> > --- a/drivers/i2c/busses/i2c-imx-lpi2c.c
> > +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
> > @@ -1309,7 +1309,7 @@ static int lpi2c_imx_probe(struct platform_device
> *pdev)
> >       if (ret)
> >               lpi2c_imx->bitrate = I2C_MAX_STANDARD_MODE_FREQ;
> >
> > -     ret = devm_request_irq(&pdev->dev, irq, lpi2c_imx_isr, 0,
> > +     ret = devm_request_irq(&pdev->dev, irq, lpi2c_imx_isr,
> > + IRQF_NO_SUSPEND,
> >                              pdev->name, lpi2c_imx);
> >       if (ret)
> >               return dev_err_probe(&pdev->dev, ret, "can't claim irq
> > %d\n", irq);