From: Dinh Nguyen <dinguyen@kernel.org>
To: Linus Walleij <linus.walleij@linaro.org>,
Philipp Zabel <p.zabel@pengutronix.de>
Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
Daniel Thompson <daniel.thompson@linaro.org>,
Tony Luck <tony.luck@intel.com>,
Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
Kees Cook <keescook@chromium.org>, Rob Herring <robh@kernel.org>,
Anton Vorontsov <anton@enomsg.org>,
Russell King <linux@armlinux.org.uk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Colin Cross <ccross@android.com>,
Frank Rowand <frowand.list@gmail.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RESEND PATCHv4 1/1] drivers/amba: add reset control to amba bus probe
Date: Fri, 23 Aug 2019 10:42:49 -0500 [thread overview]
Message-ID: <e7e986a2-762e-674b-608b-5ee5b013935b@kernel.org> (raw)
In-Reply-To: <CACRpkdasbXuqUkO3NjMGBU_ePEBT23BS1eP-bigB0_g494LgvQ@mail.gmail.com>
On 8/23/19 4:19 AM, Linus Walleij wrote:
> On Tue, Aug 20, 2019 at 4:58 PM Dinh Nguyen <dinguyen@kernel.org> wrote:
>
>> @@ -401,6 +402,26 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
>> ret = amba_get_enable_pclk(dev);
>> if (ret == 0) {
>> u32 pid, cid;
>> + int count;
>> + struct reset_control *rstc;
>> +
>> + /*
>> + * Find reset control(s) of the amba bus and de-assert them.
>> + */
>> + count = reset_control_get_count(&dev->dev);
>> + while (count > 0) {
>> + rstc = of_reset_control_get_shared_by_index(dev->dev.of_node, count - 1);
>> + if (IS_ERR(rstc)) {
>> + if (PTR_ERR(rstc) == -EPROBE_DEFER)
>> + ret = -EPROBE_DEFER;
>> + else
>> + dev_err(&dev->dev, "Can't get amba reset!\n");
>> + break;
>> + }
>> + reset_control_deassert(rstc);
>> + reset_control_put(rstc);
>> + count--;
>> + }
>
> I'm not normally a footprint person, but the looks of the stubs in
> <linux/reset.h> makes me suspicious whether this will have zero impact
> in size on platforms without reset controllers.
>
> Can you just ls -al on the kernel without CONFIG_RESET_CONTROLLER
> before and after this patch and ascertain that it has zero footprint effect?
Thanks for the review. I checked it, and indeed, it does have a zero
footprint effect.
>
> If it doesn't I'd sure like to break this into its own function and
> stick a if (!IS_ENABLED(CONFIG_RESET_CONTROLLER)) return 0;
> in there to make sure the compiler drops it.
>
> Also it'd be nice to get Philipp's ACK on the semantics, though they
> look correct to me.
>
Dinh
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next prev parent reply other threads:[~2019-08-23 15:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 14:58 [RESEND PATCHv4 0/1] drivers/amba: add reset control to amba Dinh Nguyen
2019-08-20 14:58 ` [RESEND PATCHv4 1/1] drivers/amba: add reset control to amba bus probe Dinh Nguyen
2019-08-23 9:19 ` Linus Walleij
2019-08-23 15:42 ` Dinh Nguyen [this message]
2019-08-26 8:57 ` Philipp Zabel
2019-08-26 15:27 ` Dinh Nguyen
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