From: viresh.kumar@st.com (viresh kumar)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 4/6] spi/spi-pl022: calculate_effective_freq() must set rate <= requested rate
Date: Wed, 10 Aug 2011 09:06:43 +0530 [thread overview]
Message-ID: <4E41FCCB.7040609@st.com> (raw)
In-Reply-To: <CACRpkdYAkPtOkVuF-UhpFHugvZpw_owmgoxP_opF8KE=cYF95w@mail.gmail.com>
[Probably you missed reply-all by mistake, so adding them again]
On 08/10/2011 01:34 AM, Linus Walleij wrote:
> On Tue, Aug 9, 2011 at 1:05 PM, Viresh Kumar <viresh.kumar@st.com> wrote:
>
>> There were few issues with calculate_effective_freq() routine:
>> - It was returning first rate found >= requested rate. Now, if system have spi's
>> rate as 83 MHz, with possible prescaled rates as 83, 41.5, 20.75, 13.83 (as we
>> can prescale with multiples of 2). If user has given rate to be programmed as
>> 22 MHz, then driver programmes it to 41.5 MHz. This looks to be incorrect, as
>> user might have given the upper limit of the device, and we are programming it
>> above it.
>> - Driver finds the first satisfying rate and programmes it, but with other
>> values of scr & cpsdvsr, it is possible to get more closer rate.
>
> Good that you found this bug!
>
>> +#define SPI_RATE(rate, cpsdvsr, scr) (rate / (cpsdvsr * (1 + scr)))
>
> Can you use a static inline instead of a macro? It is often preferred.
> If you do, this is Acked-by.
>
Not a problem. Will surely do that.
--
viresh
next prev parent reply other threads:[~2011-08-10 3:36 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-09 11:05 [PATCH 0/6] spi/spi-pl022 fixes Viresh Kumar
2011-08-09 11:05 ` [PATCH 1/6] spi/spi-pl022: Resolve formatting issues Viresh Kumar
2011-08-09 11:05 ` [PATCH 2/6] spi/spi-pl022: Use GFP_NOWAIT for allocation from tasklet Viresh Kumar
2011-08-09 11:26 ` Jassi Brar
2011-08-10 3:27 ` viresh kumar
2011-08-09 11:05 ` [PATCH 3/6] spi/spi-pl022: Don't allocate more sg than required Viresh Kumar
2011-08-09 11:05 ` [PATCH 4/6] spi/spi-pl022: calculate_effective_freq() must set rate <= requested rate Viresh Kumar
[not found] ` <CACRpkdYAkPtOkVuF-UhpFHugvZpw_owmgoxP_opF8KE=cYF95w@mail.gmail.com>
2011-08-10 3:36 ` viresh kumar [this message]
2011-08-09 11:05 ` [PATCH 5/6] spi/spi-pl022: Call pl022_dma_remove(pl022) only if enable_dma is true Viresh Kumar
2011-08-09 11:05 ` [PATCH 6/6] spi/spi-pl022: Request/free DMA channels as and when required Viresh Kumar
2011-08-09 20:10 ` [PATCH 0/6] spi/spi-pl022 fixes Linus Walleij
2011-08-10 3:55 ` viresh kumar
2011-08-10 7:20 ` Linus Walleij
2011-08-10 14:12 ` Arnd Bergmann
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