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From: Linus Walleij <linus.walleij@linaro.org>
To: Vitaly Wool <vitalywool@gmail.com>
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>
Subject: Re: [PATCH 1/2] spi/pl022: timeout on polled transfer v2
Date: Thu, 19 May 2011 19:36:23 +0200	[thread overview]
Message-ID: <BANLkTi=mQbPt9rcqEVyMLy3rkF2D7FMh=g@mail.gmail.com> (raw)
In-Reply-To: <BANLkTi=s4nzi=5f+Vvh3ABuspnKXQVUfLw@mail.gmail.com>

2011/5/19 Vitaly Wool <vitalywool@gmail.com>:

>> +
>> +               timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
>> +               while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
>> +                       time = jiffies;
>>                        readwriter(pl022);
>> +                       if (time_after(time, timeout)) {
>> +                               dev_warn(&pl022->adev->dev,
>> +                               "%s: timeout!\n", __func__);
>> +                               message->state = STATE_ERROR;
>> +                               goto out;
>> +                       }
>> +               }
>
> 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

WARNING: multiple messages have this Message-ID (diff)
From: linus.walleij@linaro.org (Linus Walleij)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] spi/pl022: timeout on polled transfer v2
Date: Thu, 19 May 2011 19:36:23 +0200	[thread overview]
Message-ID: <BANLkTi=mQbPt9rcqEVyMLy3rkF2D7FMh=g@mail.gmail.com> (raw)
In-Reply-To: <BANLkTi=s4nzi=5f+Vvh3ABuspnKXQVUfLw@mail.gmail.com>

2011/5/19 Vitaly Wool <vitalywool@gmail.com>:

>> +
>> + ? ? ? ? ? ? ? timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
>> + ? ? ? ? ? ? ? while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
>> + ? ? ? ? ? ? ? ? ? ? ? time = jiffies;
>> ? ? ? ? ? ? ? ? ? ? ? ?readwriter(pl022);
>> + ? ? ? ? ? ? ? ? ? ? ? if (time_after(time, timeout)) {
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? dev_warn(&pl022->adev->dev,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "%s: timeout!\n", __func__);
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? message->state = STATE_ERROR;
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? goto out;
>> + ? ? ? ? ? ? ? ? ? ? ? }
>> + ? ? ? ? ? ? ? }
>
> 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

  reply	other threads:[~2011-05-19 17:36 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-19 16:05 [PATCH 1/2] spi/pl022: timeout on polled transfer v2 Linus Walleij
2011-05-19 16:05 ` Linus Walleij
2011-05-19 16:55 ` Grant Likely
2011-05-19 16:55   ` Grant Likely
     [not found] ` <1305821134-26147-1-git-send-email-linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
2011-05-19 17:04   ` Vitaly Wool
2011-05-19 17:04     ` Vitaly Wool
2011-05-19 17:36     ` Linus Walleij [this message]
2011-05-19 17:36       ` Linus Walleij
2011-05-19 17:40       ` Vitaly Wool
2011-05-19 17:40         ` Vitaly Wool
2011-05-19 18:06         ` Linus Walleij
2011-05-19 18:06           ` Linus Walleij

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