linux-kernel - Re: [PATCH 01/10] spi: dw: Add support for polled operation via no IRQ specified in DT

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Date:   Tue, 19 May 2020 12:25:58 +0200
From:   Lars Povlsen <lars.povlsen@...rochip.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Lars Povlsen <lars.povlsen@...rochip.com>,
        Mark Brown <broonie@...nel.org>, SoC Team <soc@...nel.org>,
        "Microchip Linux Driver Support" <UNGLinuxDriver@...rochip.com>,
        linux-spi <linux-spi@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Serge Semin <Sergey.Semin@...kalelectronics.ru>
Subject: Re: [PATCH 01/10] spi: dw: Add support for polled operation via no IRQ specified in DT


Andy Shevchenko writes:

> On Wed, May 13, 2020 at 5:03 PM Lars Povlsen <lars.povlsen@...rochip.com> wrote:
>>
>> With this change a SPI controller can be added without having a IRQ
>> associated, and causing all transfers to be polled. For SPI controllers
>> without DMA, this can significantly improve performance by less
>> interrupt handling overhead.
>
> ...
>
>> +#define VALID_IRQ(i) (i >= 0)
>
> drivers/rtc/rtc-cmos.c:95:#define is_valid_irq(n)               ((n) > 0)
>
> Candidate to be in include/linux/irq.h ?
>
> ...
>
>> +       if (VALID_IRQ(dws->irq))
>> +               free_irq(dws->irq, master);
>
> Isn't free_irq() aware of invalid ones (not found IRQ in the tree or
> any other backend container won't do anything)?
>
>
>>  err_free_master:
>>         spi_controller_put(master);
>>         return ret;
>> --
>> 2.26.2

I'll rework this with Serge.

Thank you!

-- 
Lars Povlsen,
Microchip