mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Mark Brown <broonie@kernel.org>
To: Jean-Michel Hautbois <jean-michel.hautbois@veo-labs.com>
Cc: linux-spi@vger.kernel.org, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: spi-imx: wait_for_completion should timeout even in non-DMA transfer cases
Date: Tue, 22 Sep 2015 10:29:19 -0700	[thread overview]
Message-ID: <20150922172919.GK30445@sirena.org.uk> (raw)
In-Reply-To: <CAH-u=816w-uGmWt-sf2AqahRL2j7RBCah8JAKOCXFFnvVdMzhw@mail.gmail.com>

[-- Attachment #1: Type: text/plain, Size: 651 bytes --]

On Mon, Sep 21, 2015 at 11:08:55AM +0200, Jean-Michel Hautbois wrote:
> 2015-09-19 19:56 GMT+02:00 Mark Brown <broonie@kernel.org>:

> > A calculated timeout is probably best.

> Well, it depends...
> If you have a 20MHz clock, then you can transfer a byte in 4µs.
> As most of the time pio_transfer is used for 8 to 32 bytes max, it
> would be irrelevant to use such a small timeout.
> I can obviously do it, but not sure if using a small (say, 100ms)
> timeout would not be better.

You want a minimum threashold, yes, but you also need to be able toc ope
with larger transfers too so need to be able to raise that where
appropriate.

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 473 bytes --]

      reply	other threads:[~2015-09-22 17:29 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-18 12:38 Jean-Michel Hautbois
2015-09-19 17:56 ` Mark Brown
2015-09-21  9:08   ` Jean-Michel Hautbois
2015-09-22 17:29     ` Mark Brown [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20150922172919.GK30445@sirena.org.uk \
    --to=broonie@kernel.org \
    --cc=jean-michel.hautbois@veo-labs.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-spi@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

all inboxes | Powered by JetHome®