Re: [PATCH] spi: Add HiSilicon SPI controller driver support

From: Jay Fang <f.fangjian@huawei.com>
To: Lukas Wunner <lukas@wunner.de>, Mark Brown <broonie@kernel.org>
Cc: <linux-spi@vger.kernel.org>, <huangdaode@huawei.com>
Subject: Re: [PATCH] spi: Add HiSilicon SPI controller driver support
Date: Tue, 9 Mar 2021 17:13:50 +0800	[thread overview]
Message-ID: <1ec74012-f5b4-214a-ed35-d9031e94e000@huawei.com> (raw)
In-Reply-To: <20210307144313.GA15472@wunner.de>

On 2021/3/7 22:43, Lukas Wunner wrote:
> On Mon, Mar 01, 2021 at 01:54:05PM +0000, Mark Brown wrote:
>> On Mon, Mar 01, 2021 at 07:56:11PM +0800, Jay Fang wrote:
>>> +	ret = devm_request_irq(dev, hs->irq, hisi_spi_irq, IRQF_SHARED,
>>> +				dev_name(dev), master);
>>> +	if (ret < 0) {
>>> +		dev_err(dev, "failed to get IRQ=%d, ret=%d\n", hs->irq, ret);
>>> +		return ret;
>>> +	}
>>
>> This will free the IRQ *after* the controller is unregistered, it's
>> better to manually free the interrupt
> 
> Transfers may still be ongoing until spi_unregister_controller() returns.
> (It's called from devres_release_all() in this case.)  Since the IRQ is
> presumably necessary to handle those transfers, freeing the IRQ after
> unregistering is actually correct.  So the code looks fine in principle.
> 
> However, because the IRQ is requested with IRQF_SHARED, the handler may
> be invoked at any time, even after the controller has been unregistered.
> It is therefore necessary to quiesce the SPI controller's interrupt on
> unregistering and it is also necessary to check in the IRQ handler whether
> an interrupt is actually pending (and bail out if not).
>
Thanks for your review. I will consider not using IRQF_SHARED IRQ here.


Thanks
Jay