Re: [PATCH v8 2/4] misc: Generic on-chip SRAM allocation driver

Philipp Zabel
2013-02-11T18:15:34Z

Hi Grant,

Am Freitag, den 08.02.2013, 20:16 +0000 schrieb Grant Likely:
> On Mon, 4 Feb 2013 12:32:16 +0100, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> > This driver requests and remaps a memory region as configured in the
> > device tree. It serves memory from this region via the genalloc API.
> > It optionally enables the SRAM clock.
> >
> > Other drivers can retrieve the genalloc pool from a phandle pointing
> > to this drivers' device node in the device tree.
> >
> > The allocation granularity is hard-coded to 32 bytes for now,
> > to make the SRAM driver useful for the 6502 remoteproc driver.
> > There is overhead for bigger SRAMs, where only a much coarser
> > allocation granularity is needed: At 32 bytes minimum allocation
> > size, a 256 KiB SRAM needs a 1 KiB bitmap to track allocations.
> >
> > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> > Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
> > ---
> > Changes since v7:
> > - Removed obsolete __devinit/__devexit/__devexit_p
> > ---
> > Documentation/devicetree/bindings/misc/sram.txt | 17 ++++
> > drivers/misc/Kconfig | 9 ++
> > drivers/misc/Makefile | 1 +
> > drivers/misc/sram.c | 121 +++++++++++++++++++++++
> > 4 files changed, 148 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/misc/sram.txt
> > create mode 100644 drivers/misc/sram.c
> >
> > diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt
> > new file mode 100644
> > index 0000000..b64136c
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/misc/sram.txt
> > @@ -0,0 +1,17 @@
> > +Generic on-chip SRAM
> > +
> > +Simple IO memory regions to be managed by the genalloc API.
> > +
> > +Required properties:
> > +
> > +- compatible : sram
>
> I'm a little concerned that 'sram' is just too generic for a compatible
> value and we may end up needing a blacklist of systems where the sram
> device should not be driven with this driver. If you can think of
> a more descriptive name here then I would use it.

various SoC vendors call this (variations of) "on-chip" or "internal"
SRAM/memory. "on-chip-sram" or "internal-sram" are still plenty generic,
though. How about "mmio-sram", as opposed to an SRAM that needs more
than the simple mmio region handled by this driver?

An alternative would be to use the vendor specific names and grow a
compatible list in the driver ("fsl,ocram", "ti,ocm", ...).

> However, I'm not worried about it enough to nak it and the rest of the
> series looks fine.
>
> Acked-by: Grant Likely <grant.likely@secretlab.ca>

Thank you.

regards
Philipp