From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Subject: Re: [PATCH] i2c: mxs: remove broken PIOQUEUE support Date: Thu, 1 Nov 2012 15:28:17 +0100 Message-ID: <201211011528.17596.marex@denx.de> References: <1351771003-6071-1-git-send-email-w.sang@pengutronix.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1351771003-6071-1-git-send-email-w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Shawn Guo List-Id: linux-i2c@vger.kernel.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 Thanks [...] Best regards, Marek Vasut