From: Shawn Guo <shawn.guo@linaro.org>
To: Richard Zhao <richard.zhao@freescale.com>
Cc: Eric Miao <eric.miao@linaro.org>,
patches@linaro.org, vinod.koul@intel.com,
linux-kernel@vger.kernel.org, kernel@pengutronix.de,
dan.j.williams@intel.com, Richard Zhao <richard.zhao@linaro.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 6/6] dma/imx-sdma: check whether event_id0 < 32 when set event_mask
Date: Wed, 11 Jan 2012 21:35:00 +0800 [thread overview]
Message-ID: <20120111133458.GD20968@S2101-09.ap.freescale.net> (raw)
In-Reply-To: <20120111130910.GC27484@b20223-02.ap.freescale.net>
On Wed, Jan 11, 2012 at 09:09:11PM +0800, Richard Zhao wrote:
> On Wed, Jan 11, 2012 at 09:16:17PM +0800, Shawn Guo wrote:
> > On Wed, Jan 11, 2012 at 02:37:08PM +0800, Eric Miao wrote:
> > > I think Richard has made the issue quite clear here, the original
> >
> > Yes, he has made it clear, but only after I asked for more comments,
> > not with the empty commit message.
> >
> > > code does seem to have some problems even to me, who do not
> > > understand the very details of the SDMA:
> > >
> > > - sdmac->event_mask0 = 1 << sdmac->event_id0;
> > > - sdmac->event_mask1 = 1 << (sdmac->event_id0 - 32);
> > >
> > > 1. if sdmac->event_id0 >= 32, which will cause event_mask0 to be incorrect
> > > 2. if sdmac->event_id < 32, sdmac->event_mask1 will be incorrect
> > >
> > My testing tells this is not the case. The event_mask0 will be 0 in
> > case 1) and event_mask1 will be 0 in case 2), which is quite what we
> > expect. And I do not believe you will see any functionality bug with
> > the existing code.
> Please see my mail mentioned "we shoud not let it depends on gcc's
> behavior."
In this case, I would rather believe that the author is smart enough
to write the code intentionally based on his good understanding on
behavior of arm-gcc.
--
Regards,
Shawn
next prev parent reply other threads:[~2012-01-11 13:24 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-10 7:01 [PATCH 1/6] dma/imx-sdma: let sdma_run_channel call sdma_enable_channel Richard Zhao
2012-01-10 7:01 ` [PATCH 2/6] dma/imx-sdma: use readl_relaxed/writel_relaxed and use writel when necessary Richard Zhao
2012-01-10 7:01 ` [PATCH 3/6] dma/imx-sdma: call sdma_set_channel_priority after sdma_request_channel Richard Zhao
2012-01-10 7:01 ` [PATCH 4/6] dma/imx-sdma: move clk_enable out of sdma_request_channel Richard Zhao
2012-01-10 7:01 ` [PATCH 5/6] dma/imx-sdma: use num_events to validate event_id0 Richard Zhao
2012-01-10 14:02 ` Dirk Behme
2012-01-10 14:16 ` Shawn Guo
2012-01-10 7:01 ` [PATCH 6/6] dma/imx-sdma: check whether event_id0 < 32 when set event_mask Richard Zhao
2012-01-10 14:20 ` Shawn Guo
2012-01-10 14:29 ` Richard Zhao
2012-01-10 15:38 ` Shawn Guo
2012-01-11 0:53 ` Richard Zhao
2012-01-11 1:47 ` Richard Zhao
2012-01-11 6:37 ` Eric Miao
2012-01-11 12:35 ` Richard Zhao
2012-01-11 12:53 ` Richard Zhao
2012-01-12 14:23 ` Richard Zhao
2012-01-11 13:16 ` Shawn Guo
2012-01-11 13:09 ` Richard Zhao
2012-01-11 13:35 ` Shawn Guo [this message]
2012-01-11 13:48 ` Eric Miao
2012-01-11 13:11 ` Shawn Guo
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