From mboxrd@z Thu Jan  1 00:00:00 1970
From: Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH 1/2] spi/pl022: timeout on polled transfer v2
Date: Thu, 19 May 2011 19:36:23 +0200
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Cc: Grant Likely <grant.likely@secretlab.ca>,
	spi-devel-general@lists.sourceforge.net, Lee Jones <lee.jones@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	Magnus Templing <magnus.templing@stericsson.com>
To: Vitaly Wool <vitalywool@gmail.com>
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2011/5/19 Vitaly Wool <vitalywool@gmail.com>:

>> +
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 timeout =3D jiffies + msecs_to_jiffies(SPI=
_POLLING_TIMEOUT);
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 while (pl022->tx < pl022->tx_end || pl022-=
>rx < pl022->rx_end) {
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 time =3D jiffies;
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0readwriter(pl022);
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (time_after(time, timeo=
ut)) {
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 dev_warn(&=
pl022->adev->dev,
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 "%s: timeo=
ut!\n", __func__);
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 message->s=
tate =3D STATE_ERROR;
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto out;
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
>
> just out of curiosity: is it a busy wait? Looks like it is...

Yep that's the polling mode part. IRQ and DMA mode should
be the norm I guess.

Magnus: do you have a specific use case for this thing?

Yours,
Linus Walleij