linux-kernel - RE: [PATCH v3 1/1] i2c: ocores: fix polling mode workaround on FU540-C000 SoC

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Message-ID: <DM6PR13MB3451CA7C440D0E2F94AAF1C597030@DM6PR13MB3451.namprd13.prod.outlook.com>
Date:   Fri, 16 Oct 2020 04:23:31 +0000
From:   Sagar Kadam <sagar.kadam@...nfive.com>
To:     Peter Korsgaard <peter@...sgaard.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "Paul Walmsley ( Sifive)" <paul.walmsley@...ive.com>,
        "palmer@...belt.com" <palmer@...belt.com>,
        "aou@...s.berkeley.edu" <aou@...s.berkeley.edu>
Subject: RE: [PATCH v3 1/1] i2c: ocores: fix polling mode workaround on
 FU540-C000 SoC

Hello Peter,

> -----Original Message-----
> From: Peter Korsgaard <jacmet@...il.com> On Behalf Of Peter Korsgaard
> Sent: Thursday, October 15, 2020 8:19 PM
> To: Sagar Kadam <sagar.kadam@...nfive.com>
> Cc: linux-kernel@...r.kernel.org; linux-riscv@...ts.infradead.org; linux-
> i2c@...r.kernel.org; andrew@...n.ch; Paul Walmsley ( Sifive)
> <paul.walmsley@...ive.com>; palmer@...belt.com;
> aou@...s.berkeley.edu
> Subject: Re: [PATCH v3 1/1] i2c: ocores: fix polling mode workaround on
> FU540-C000 SoC
> 
> [External Email] Do not click links or attachments unless you recognize the
> sender and know the content is safe
> 
> >>>>> "Sagar" == Sagar Shrikant Kadam <sagar.kadam@...ive.com> writes:
> 
>  > The FU540-C000 has a broken IRQ and support was added earlier
>  > so that it will operate in polling mode, but seems to work only
>  > in case interrupts property is missing from the i2c0 dt-node.
>  > This should not be the case and the driver should handle polling
>  > mode with the interrupt property present in i2c0 node of the
>  > device tree.
>  > So check if it's the FU540-C000 soc and enable polling mode master
>  > xfers, as the IRQ for this chip is broken.
> 
>  > Fixes commit c45d4ba86731 ("i2c: ocores: add polling mode workaround
>  > for Sifive FU540-C000 SoC")
> 
>  > Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@...ive.com>
>  > ---
>  >  drivers/i2c/busses/i2c-ocores.c | 22 +++++++++++++---------
>  >  1 file changed, 13 insertions(+), 9 deletions(-)
> 
>  > diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-
> ocores.c
>  > index f5fc75b..1dab02d 100644
>  > --- a/drivers/i2c/busses/i2c-ocores.c
>  > +++ b/drivers/i2c/busses/i2c-ocores.c
>  > @@ -686,17 +686,21 @@ static int ocores_i2c_probe(struct
> platform_device *pdev)
> 
>  >      init_waitqueue_head(&i2c->wait);
> 
>  > +    /*
>  > +     * Set OCORES_FLAG_BROKEN_IRQ to enable workaround for
>  > +     * FU540-C000 SoC in polling mode.
>  > +     * Since the SoC does have interrupt its dt has the interrupt
>  > +     * defined but it should be bypassed in driver as this SoC has
> 
> NIT: Looks like there some commas missing and the wording sounds a bit
> odd to me. What about E.G.:
> 
Sorry for the confusing wordings here.
>      /*
>       * Since the SoC does have an interrupt, its DT has an interrupt
>       * property - But this should be bypassed as the IRQ logic in this
>       * SoC is broken.
>       */
> 
I will replace mine with your suggested one.

>  > +     * a broken IRQ, hence update the master_xfer to use polling
>  > +     * transfers.
>  > +     */
>  > +    if (of_device_is_compatible(pdev->dev.of_node,
>  > +                                "sifive,fu540-c000-i2c"))
>  > +            i2c->flags |= OCORES_FLAG_BROKEN_IRQ;
>  > +
>  >      irq = platform_get_irq(pdev, 0);
>  > -    if (irq == -ENXIO) {
>  > +    if (i2c->flags & OCORES_FLAG_BROKEN_IRQ || irq == -ENXIO) {
> 
> 
> Alternatively you can move it after the irq = platform_get_irq(pdev, 0)
> line and just clear irq, E.G.:
> 
> irq = platform_get_irq(pdev, 0);
> 
> if (of_device_is_compatible(..)) {
>    i2c->flags |= OCORES_FLAG_BROKEN_IRQ;
>    irq = -ENXIO;
> }
> 
Yeah..
This is a better alternative implementation.
I will push v4 with this.

Thanks & BR,
Sagar

> if (irq == -ENXIO) {
> ..
> 
> --
> Bye, Peter Korsgaard