linux-kernel - Re: [PATCH] firmware: arm_scmi: Use {get,put}_unaligned

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Date:   Wed, 7 Aug 2019 14:57:58 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Philipp Zabel <p.zabel@...gutronix.de>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH] firmware: arm_scmi: Use {get,put}_unaligned_le32
 accessors

On Wed, Aug 07, 2019 at 03:36:11PM +0200, Philipp Zabel wrote:
> Hi Sudeep,
>
> On Wed, 2019-08-07 at 14:00 +0100, Sudeep Holla wrote:
> > Instead of type-casting the {tx,rx}.buf all over the place while
> > accessing them to read/write __le32 from/to the firmware, let's use
> > the nice existing {get,put}_unaligned_le32 accessors to hide all the
> > type cast ugliness.
> >
> > Suggested-by: Philipp Zabel <p.zabel@...gutronix.de>
> > Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> > ---
> >  drivers/firmware/arm_scmi/base.c    |  2 +-
> >  drivers/firmware/arm_scmi/clock.c   | 10 ++++------
> >  drivers/firmware/arm_scmi/common.h  |  2 ++
> >  drivers/firmware/arm_scmi/perf.c    |  8 ++++----
> >  drivers/firmware/arm_scmi/power.c   |  6 +++---
> >  drivers/firmware/arm_scmi/reset.c   |  2 +-
> >  drivers/firmware/arm_scmi/sensors.c | 12 +++++-------
> >  7 files changed, 20 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
> > index 204390297f4b..f804e8af6521 100644
> > --- a/drivers/firmware/arm_scmi/base.c
> > +++ b/drivers/firmware/arm_scmi/base.c
> [...]
> > @@ -204,14 +204,12 @@ scmi_clock_rate_get(const struct scmi_handle *handle, u32 clk_id, u64 *value)
> >  	if (ret)
> >  		return ret;
> >
> > -	*(__le32 *)t->tx.buf = cpu_to_le32(clk_id);
> > +	put_unaligned_le32(clk_id, t->tx.buf);
> >
> >  	ret = scmi_do_xfer(handle, t);
> >  	if (!ret) {
> > -		__le32 *pval = t->rx.buf;
> > -
> > -		*value = le32_to_cpu(*pval);
> > -		*value |= (u64)le32_to_cpu(*(pval + 1)) << 32;
> > +		*value = get_unaligned_le32(t->rx.buf);
> > +		*value |= (u64)get_unaligned_le32(t->rx.buf + 1) << 32;
>
> Isn't t->rx.buf a void pointer? If I am not mistaken, you'd either have
> to keep the pval local variables, or cast to (__le32 *) before doing
> pointer arithmetic.
>

Ah right, that's the reason I added it at the first place. I will fix that.

--
Regards,
Sudeep