Messages in this thread | | | Date | Sun, 22 Apr 2012 23:55:06 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH V2 1/3] lib: add support for stmp-style devices |
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On Wed, 21 Mar 2012 23:21:57 +0100 Wolfram Sang <w.sang@pengutronix.de> wrote:
> MX23/28 use IP cores which follow a register layout I have first seen on > STMP3xxx SoCs. In this layout, every register actually has four u32: > > 1.) to store a value directly > 2.) a SET register where every 1-bit sets the corresponding bit, > others are unaffected > 3.) same with a CLR register > 4.) same with a TOG (toggle) register > > Also, the 2 MSBs in register 0 are always the same and can be used to reset > the IP core. > > All this is strictly speaking not mach-specific (but IP core specific) and, > thus, doesn't need to be in mach-mxs/include. At least, mx6 and mx50 also > utilize IP cores following this stmp-style. So: > > Introduce a stmp-style device, put the code and defines for that in a public > place (lib/), and let drivers for stmp-style devices select that code. > To avoid regressions and ease reviewing, the actual code is simply copied from > mach-mxs. It definately wants updates, but those need a seperate patch series. > > Voila, mach dependency gone, reusable code introduced. Note that I didn't > remove the duplicated code from mach-mxs yet, first the drivers have to be > converted. > > ... > > include/linux/stmp_device.h | 20 +++++++++++ > lib/Kconfig | 3 ++ > lib/Makefile | 2 + > lib/stmp_device.c | 80 +++++++++++++++++++++++++++++++++++++++++++
It's good that this is being presented as library code, rather than being buried in some device-specific directory then copied and pasted ten times.
But ./lib/ does seem rather a strange place for it. Perhaps we need a drivers/lib/ or something. We can use ./lib/ for now - it can always be moved later on.
> --- /dev/null > +++ b/lib/stmp_device.c
The functions in this file look terribly racy on SMP, or even with preemption or interrupts. What happens if two CPUs or threads run stmp_reset_block() against the same device at the same time?
Perhaps the caller is supposed to prevent that, and the documentation which isn't there forgot to mention it ;)
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