Re: [PATCH] clk: qcom: Specify LE device endianness

From: Stephen Boyd
Date: Fri Nov 20 2015 - 16:14:20 EST

On 11/20, Tyler Baker wrote:
> On 9 November 2015 at 14:30, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote:
> > All these clock controllers are little endian devices, but so far
> > we've been relying on the regmap mmio bus handling this for us
> > without explicitly stating that fact. After commit 4a98da2164cf
> > (regmap-mmio: Use native endianness for read/write, 2015-10-29),
> > the regmap mmio bus will read/write with the __raw_*() IO
> > accessors, instead of using the readl/writel() APIs that do
> > proper byte swapping for little endian devices.
> >
> > So if we're running on a big endian processor and haven't
> > specified the endianness explicitly in the regmap config or in
> > DT, we're going to switch from doing little endian byte swapping
> > to big endian accesses without byte swapping, leading to some
> > confusing results. On my apq8074 dragonboard, this causes the
> > device to fail to boot as we access the clock controller with
> > big endian IO accesses even though the device is little endian.
> >
> > Specify the endianness explicitly so that the regmap core
> > properly byte swaps the accesses for us.
> >
> > Reported-by: Kevin Hilman <khilman@xxxxxxxxxx>
> > Cc: Simon Arlott <simon@xxxxxxxxxxx>
> > Cc: Mark Brown <broonie@xxxxxxxxxx>
> > Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> Tested-by: Tyler Baker <tyler.baker@xxxxxxxxxx>
> The bot also reported boot failures[1] for the
> apq8016-sbc in next-20151120 with CONFIG_CPU_BIG_ENDIAN=y enabled.
> I've bisected the failure down to the same offending remap-mmio patch
> listed above. I've confirmed this patch applied on top of
> next-20151120 fixes the boot issue for the apq8016-sbc as well.
> Any updates or comments on this patch? I'd like to see this fix in
> linux-next, as it has been broken for over a week and could be masking
> new issues.

Yeah I've been lagging on applying patches. I need to send more
patches for other regmap-mmio users too. I'll cook those up right
now and send them off.

Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at