linux-kernel - Re: [PATCH v3 04/13] clk: at91: make IRQ optional and register them later

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Date:	Fri, 22 Jan 2016 16:40:35 +0100
From:	Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:	Nicolas Ferre <nicolas.ferre@...el.com>,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 04/13] clk: at91: make IRQ optional and register them
 later

On 2015-12-04 18:03:39 [+0100], Alexandre Belloni wrote:
> diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
> index 295b17b9c689..296d20a29c6c 100644
> --- a/drivers/clk/at91/pmc.c
> +++ b/drivers/clk/at91/pmc.c
> @@ -20,6 +20,9 @@
…
> +	pmc->irqdomain = irq_domain_add_linear(pdev->dev.of_node, 32,
> +					       &pmc_irq_ops, pmc);
> +	if (!pmc->irqdomain)
> +		return 0;
>  
> -static void __init of_at91sam9n12_pmc_setup(struct device_node *np)
> -{
> -	of_at91_pmc_setup(np, &at91sam9n12_caps);
> -}
> -CLK_OF_DECLARE(at91sam9n12_clk_pmc, "atmel,at91sam9n12-pmc",
> -	       of_at91sam9n12_pmc_setup);
> +	regmap_write(pmc->regmap, AT91_PMC_IDR, 0xffffffff);
> +	ret = request_irq(pmc->virq, pmc_irq_handler,
> +			  IRQF_SHARED | IRQF_COND_SUSPEND, "pmc", pmc);

You need IRQF_NOTHREAD here becuase pmc_irq_handler() is demuxing
interrupts / invoking generic_handle_irq().
However regmap_read() inside pmc_irq_handler() is taking a sleeping lock
on -RT so this is not going to fly. So either get rid regmap_read() in
the handler or use handle_nested_irq() instead.

> +	if (ret)
> +		return ret;

Sebastian