linux-kernel - Re: [PATCH v2 1/4] clk: bcm2835: More flexible IO register remapping

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Date:   Mon, 12 Jun 2017 11:19:38 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Phil Elwell <phil@...pberrypi.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Eric Anholt <eric@...olt.net>,
        Russell King <linux@...linux.org.uk>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-rpi-kernel@...ts.infradead.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 1/4] clk: bcm2835: More flexible IO register remapping

On 06/12/2017 07:25 AM, Phil Elwell wrote:
> The BCM2835 AUX block contains two registers - AUXIRQ and AUXENB.
> The addition of an irqchip driver using AUXIRQ is hampered by
> the current DT node reserving both registers with a compatible string
> claimed by this bcm2835-aux-clk driver.
> 
> Ease the transition to separate DT nodes by detecting and handling
> the case where this driver's MEM resource has been reduced to include
> only the AUXENB register. Otherwise, use devm_ioremap to remap the
> region without reserving it.
> 
> Signed-off-by: Phil Elwell <phil@...pberrypi.org>
> ---
>  drivers/clk/bcm/clk-bcm2835-aux.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/bcm/clk-bcm2835-aux.c b/drivers/clk/bcm/clk-bcm2835-aux.c
> index bd750cf..70d389e 100644
> --- a/drivers/clk/bcm/clk-bcm2835-aux.c
> +++ b/drivers/clk/bcm/clk-bcm2835-aux.c
> @@ -37,9 +37,22 @@ static int bcm2835_aux_clk_probe(struct platform_device *pdev)
>  	parent = __clk_get_name(parent_clk);
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	reg = devm_ioremap_resource(dev, res);
> -	if (IS_ERR(reg))
> -		return PTR_ERR(reg);
> +	/*
> +	 * If the MEM resource is only 4 bytes long it covers just the
> +	 * AUXENB register, otherwise it is the entire AUX block.
> +	 */

Would be worth commenting why devm_ioremap_resource() is used here (to
avoid the implicit request mem_region) and not in the other case. Might
also be worth adding a comment that explains that this is temporary and
this kludge should be removed in the future in favor of the new bindings
only.

Thanks!
-- 
Florian