From: Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>
To: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Shawn Guo <shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH] i2c: mxs: remove broken PIOQUEUE support
Date: Thu, 1 Nov 2012 15:28:17 +0100 [thread overview]
Message-ID: <201211011528.17596.marex@denx.de> (raw)
In-Reply-To: <1351771003-6071-1-git-send-email-w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Dear Wolfram Sang,
> This I2C master can do DMA and PIOQUEUE (PIO with FIFO). Originally,
> only PIOQEUE
PIOQUEUE ;-)
> was supported, then DMA support was added. The original
> intention was to keep PIOQUEUE since it has less overhead what is nice
> for small transfers. However, runtime switching between PIOQEUE and DMA
> depending on the transfer size never worked despite a lot of trying.
> Since PIOQUEUE mode itself was flaky (polling at places where interrupts
> failed to work) and the implementation also imposed a size limit for
> transfers, it is best to remove the support altogether which makes the
> driver a lot cleaner and more robust. If somebody really wants less
> overhead, plain PIO mode could still be implemented with the addidtional
> advantage that this mode is also available on MX23, too.
Yes, looks to be the way to go.
Reviewed-by: Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>
Thanks
[...]
Best regards,
Marek Vasut
next prev parent reply other threads:[~2012-11-01 14:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-01 11:56 [PATCH] i2c: mxs: remove broken PIOQUEUE support Wolfram Sang
[not found] ` <1351771003-6071-1-git-send-email-w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-01 14:28 ` Marek Vasut [this message]
[not found] ` <201211011528.17596.marex-ynQEQJNshbs@public.gmane.org>
2012-11-01 16:08 ` Wolfram Sang
[not found] ` <20121101160828.GA18425-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-11-01 16:12 ` Marek Vasut
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