From: Robin Gong <b38343@freescale.com>
To: Mark Brown <broonie@kernel.org>
Cc: <linux-arm-kernel@lists.infradead.org>,
<linux-spi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<marex@denx.de>, <shawn.guo@linaro.org>, <Frank.Li@freescale.com>
Subject: Re: [PATCH v5] spi: spi-imx: add DMA support
Date: Wed, 10 Sep 2014 23:18:01 +0800 [thread overview]
Message-ID: <20140910151759.GA31462@Robin-OptiPlex-780> (raw)
In-Reply-To: <20140910114530.GD7960@sirena.org.uk>
On Wed, Sep 10, 2014 at 12:45:30PM +0100, Mark Brown wrote:
> On Wed, Sep 10, 2014 at 07:22:59PM +0800, Robin Gong wrote:
> > On Wed, Sep 10, 2014 at 11:21:05AM +0100, Mark Brown wrote:
>
> > > This isn't going to work, anything that looks at the usedma flag will
> > > see the result of the last thing that was checked which may or may not
> > > be the transfer that it's handling. The driver should check to see if
> > > the core mapped the transfer for DMA.
>
> > Yes, you're right. I should use "transfer->tx_sg->sgl == NULL" or
> > "transfer->rx_sg->sgl == NULL" instead of usedma flag in driver, right?
>
> Right.
But looks spi core framework can make sure every rx or tx transfer in sequence.
If so, can_dma will never be called until this transfer finished
(spi_pump_messages), and my usedma flag also never be modified until next
transfer start. Please correct me if I am wrong, thanks.
next prev parent reply other threads:[~2014-09-10 15:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-10 1:30 [PATCH v5] spi: spi-imx: add DMA support Robin Gong
2014-09-10 4:16 ` Varka Bhadram
2014-09-10 5:46 ` Robin Gong
2014-09-10 8:17 ` Arnd Bergmann
2014-09-10 8:28 ` Robin Gong
2014-09-10 10:21 ` Mark Brown
2014-09-10 11:22 ` Robin Gong
2014-09-10 11:45 ` Mark Brown
2014-09-10 15:18 ` Robin Gong [this message]
2014-09-10 15:52 ` Mark Brown
2014-09-11 1:37 ` Robin Gong
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