Re: [PATCH V2 RESEND] clk: mxs: Fix invalid 32-bit access to frac registers
From: Fabio Estevam
Date: Tue Feb 10 2015 - 07:52:59 EST
On Fri, Jan 30, 2015 at 5:20 PM, Stefan Wahren <stefan.wahren@xxxxxxxx> wrote:
> According to i.MX23 and i.MX28 reference manual , the fractional
> clock control register is 32-bit wide, but is separated in 4 parts.
> So write instructions must not apply to more than 1 part at once.
> The clk init for the i.MX28 violates this restriction and all the other
> accesses on that register suggest that there isn't such a restriction.
> This patch restricts the access to this register to byte instructions and
> extends the comment in the init functions.
> Btw the imx23 init now uses a R-M-W sequence just like imx28 init
> to avoid any clock glitches.
> The changes has been tested with a i.MX23 and a i.MX28 board.
>  - http://cache.freescale.com/files/dsp/doc/ref_manual/IMX23RM.pdf
>  - http://cache.freescale.com/files/dsp/doc/ref_manual/MCIMX28RM.pdf
> Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
> Reviewed-by: Marek Vasut <marex@xxxxxxx>
> Changes in V2:
> - use relaxed access operations in clk-ref
With this patch applied mx28evk cannot probe SPI NOR flash:
m25p80 spi1.0: unrecognized JEDEC id bytes: bf, 24, 40
Reverting it from linux-next, then the SPI NOR probe correctly.
m25p80 spi1.0: sst25vf016b (2048 Kbytes)
Thanks for the suggestion, Marek!
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