linux-kernel - Re: [PATCH 3/3] spi: omap2-mcspi: Add slave mode support

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Message-ID: <87459424-1083-0716-0481-89d7b7e3f08c@ti.com>
Date:   Mon, 15 Oct 2018 15:34:37 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Vignesh R <vigneshr@...com>, Mark Brown <broonie@...nel.org>
CC:     <linux-spi@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] spi: omap2-mcspi: Add slave mode support

On Monday 15 October 2018 03:12 PM, Vignesh R wrote:
> Hi Sekhar,
> 
> On Monday 15 October 2018 01:53 PM, Sekhar Nori wrote:
> 
> [...]
>>>  
>>> +static irqreturn_t omap2_mcspi_irq_handler(int irq, void *data)
>>> +{
>>> +	struct omap2_mcspi *mcspi = data;
>>> +	u32 irqstat;
>>> +
>>> +	irqstat	= mcspi_read_reg(mcspi->master, OMAP2_MCSPI_IRQSTATUS);
>>> +	if (!irqstat)
>>> +		return IRQ_NONE;
>>> +
>>> +	/* Disable IRQ and wakeup slave xfer task */
>>> +	mcspi_write_reg(mcspi->master, OMAP2_MCSPI_IRQENABLE, 0);
>>> +	if (irqstat & OMAP2_MCSPI_IRQSTATUS_EOW)
>>> +		complete(&mcspi->txdone);
>>> +
>>> +	return IRQ_HANDLED;
>>
>> You need to have the:
>>
>> pm_runtime_get_sync();
>>
>> /* access registers */
>>
>> pm_runtime_mark_last_busy();
>> pm_runtime_put_autosuspend();
>>
>> sequence here. I think thats also missing from the dma callbacks.
>> Probably working by chance today.
>>
> 
> This is taken care of by the SPI core as part of __spi_pump_messages():
> pm_runtime_get_sync()
> ...
> spi_transfer_one_message
> ...
> 	omap2_mcspi_transfer_one
> 	...
> 		omap2_mcspi_txrx_dma
> 
> So, both in dma callbacks and in IRQ handler, SPI controller is in
> active state.

Ah, okay then. False alarm :)

Regards,
Sekhar