linux-kernel - Re: [PATCH 2/2] mrst_max3110: fix SPI UART interrupt parameters

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Message-ID: <52681128.2010404@linux.intel.com>
Date:	Wed, 23 Oct 2013 11:10:48 -0700
From:	David Cohen <david.a.cohen@...ux.intel.com>
To:	Alexander Shiyan <shc_work@...l.ru>
CC:	gregkh@...uxfoundation.org, jslaby@...e.cz, ning.li@...el.com,
	ivan.gorinov@...el.com, linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: Re: [PATCH 2/2] mrst_max3110: fix SPI UART interrupt parameters

On 10/22/2013 11:27 PM, Alexander Shiyan wrote:
>> On 10/22/2013 01:30 PM, David Cohen wrote:
>>> On 10/22/2013 12:46 PM, Alexander Shiyan wrote:
>>>>> The change in the max3110 driver makes the IRQ handling threaded, now
>>>>> the handler is called only once per received character. Without that
>>>>> change, we had many (more than 100) interrupts per one received
>>>>> character.
>>>>>
>>>>> Unfortunately, SFI interface does not support IRQ polarity and
>>>>> triggering modes, so we have to keep the hacks as hard-coded device
>>>>> names and IRQ numbers until we switch to ACPI.
>>>>>
>>>>> Edge-triggered IRQ still supported to keep old platforms working.
>>>>> Use platform data to pass the irq mode argument.
>>>>>
>>>>> Signed-off-by: Ivan Gorinov <ivan.gorinov@...el.com>
>>>>> Signed-off-by: Li Ning <ning.li@...el.com>
>>>>> Signed-off-by: David Cohen <david.a.cohen@...ux.intel.com>
>>>> ...
>>>>> +++ b/include/linux/serial_max3110.h
>>>>> @@ -0,0 +1,16 @@
>>>>> +#ifndef _LINUX_SERIAL_MAX3110_H
>>>>> +#define _LINUX_SERIAL_MAX3110_H
>>>>> +
>>>>> +/**
>>>>> + * struct plat_max3110 - MAX3110 SPI UART platform data
>>>>> + * @irq_edge_trigger: if IRQ is edge triggered
>>>>> + *
>>>>> + * You should use this structure in your machine description to specify
>>>>> + * how the MAX3110 is connected.
>>>>> + *
>>>>> + */
>>>>> +struct plat_max3110 {
>>>>> +    int irq_edge_triggered;
>>>>> +};
>>>>> +
>>>>> +#endif
>>>>> --
>>>>
>>>> Is just resource->flags for IRQ can be reused for handle such case?
>>>
>>> I believe your suggestion makes perfect sense. I'll rework it.
>>
>> Looks like isp_device has no place for 'resource'. In this case pdata
>> seems to be the way to go here.
>> Or maybe there's a better way to recommend?
>
> What do you mean by the isp_device?

Allow me to correct my typo: I meant spi_device (this is a spi
device/driver).

>
> My idea is always use threaded irq and passing flags into request.
> Like as:
> unsigned long flags = res->flags & IORESOURCE_BITS;
> ...
> request_threaded_irq(max->irq, serial_m3110_irq, IRQF_ONESHOT | flags, "max3110", max);


Oh, maybe we were talking about different things afterall :)
The reason this struct plat_max3110 was created is to allow platform
code (located under arch/x86/platform/intel-mid/device_libs/) to define
the irq edge type.
When I saw your comment I though you were referring to struct resource
(which has IORESOURCE_IRQ_* flags). But unlike platform_device,
spi_device has no struct resource * to replace the need of struct
plat_max3110.

OTOH your suggestion can replace this piece of code:

@@ -68,6 +69,7 @@ struct uart_max3110 {
         u8 clock;
         u8 parity, word_7bits;
         u16 irq;
+       u16 irq_edge_triggered;

         unsigned long uart_flags;

I'll check again the patch and possibly make the changes.

Thanks,

David Cohen
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