Re: [PATCH v3 2/2] remoteproc: meson-mx-ao-arc: Add a driver for the AO ARC remote procesor

From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: linux-remoteproc@vger.kernel.org,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, bjorn.andersson@linaro.org,
	ohad@wizery.com
Subject: Re: [PATCH v3 2/2] remoteproc: meson-mx-ao-arc: Add a driver for the AO ARC remote procesor
Date: Wed, 4 Aug 2021 23:03:57 +0200	[thread overview]
Message-ID: <CAFBinCB0-bAa7Y+YhscczarGrGuio37F8vRyfW6U2DiiDAvr-g@mail.gmail.com> (raw)
In-Reply-To: <20210728175823.GA2766167@p14s>

Hi Mathieu,

thanks for taking the time to look into this!

(I will address any of your comments that I am not mentioning in this
email anymore. Thanks a lot for the suggestions!)

On Wed, Jul 28, 2021 at 7:58 PM Mathieu Poirier
<mathieu.poirier@linaro.org> wrote:
[...]
> > +     writel(FIELD_PREP(AO_REMAP_REG0_REMAP_AHB_SRAM_BITS_17_14_FOR_ARM_CPU,
> > +                            priv->sram_pa >> 14),
> Indentation problem
The idea here is to align priv->sram_pa with AO_REMAP_REG0... which
are both arguments to FIELD_PREP
Maybe using something like this will make that easier to read:
    tmp = FIELD_PREP(AO_REMAP_REG0_REMAP_AHB_SRAM_BITS_17_14_FOR_ARM_CPU,
                                     priv->sram_pa >> 14);
    writel(tmp, priv->remap_base + AO_REMAP_REG0);

What do you think: leave it as is or use a separate variable?

[...]
> > +     usleep_range(10, 100);
>
> I've seen this kind of mysterious timeouts in other patchset based vendor trees.
> You likely don't know why it is needed so I won't ask.
unfortunately this is also the case here

[...]
> > +     priv->arc_reset = devm_reset_control_get_exclusive(dev, NULL);
> > +     if (IS_ERR(priv->arc_reset)) {
>
> Function __reset_control_get() in __devm_reset_control_get() can return NULL so
> this should be IS_ERR_OR_NULL().
The logic in there is: return optional ? NULL : ERR_PTR(-...);
I am requesting a mandatory reset line here, so reset core will never
return NULL
See also [0]

For this reason I am not planning to change this

[...]
> This driver is squeaky clean. With the above:
>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
awesome, thank you!

Best regards,
Martin

[0] https://elixir.bootlin.com/linux/v5.14-rc4/source/include/linux/reset.h#L227