Issues with cros_ec and "spi: rockchip: check return value of dmaengine_prep_slave_sg"

[Shawn Lin]

Hi Heiko,

在 2016/4/2 7:52, Heiko Stuebner 写道:
> Hi Shawn,
>
> it looks like commit ea9849113343 ("spi: rockchip: check return value of
> dmaengine_prep_slave_sg") negatively affects the cros_ec spi backend.
>
> During boot on the most recent mainline kernel I get:
>
> [    1.025480] cros-ec-spi spi0.0: Chrome EC device registered
> [    1.641636] input: cros_ec as /devices/platform/ff110000.spi/spi_master/spi0/spi0.0/ff110000.spi:ec at 0:keyboard-controller/input/input0
> [    2.340214] cros-ec-spi spi0.0: EC failed to respond in time
> [    2.357735] cros-ec-spi spi0.0: packet too long (249 bytes, expected 4)
> [    2.470353] cros-ec-spi spi0.0: EC failed to respond in time
> [    2.508495] cros-ec-spi spi0.0: packet too long (249 bytes, expected 4)
> [    2.620176] cros-ec-spi spi0.0: EC failed to respond in time
> [    2.637345] cros-ec-spi spi0.0: packet too long (249 bytes, expected 4)
> [    2.750245] cros-ec-spi spi0.0: EC failed to respond in time
> [    2.767519] cros-ec-spi spi0.0: packet too long (249 bytes, expected 4)
>
> The cros-ec works ok after boot without further errors [aka keyboard
> and everything working correctly] and I haven't been able to figure out
> what goes wrong, but was able to bisect the issue down to the commit
> mentioned above.
>

Which Soc I can reproduce it?

I'm not able to find out how this commit to break the cros-ec. So I
prone to think this commit just expose some issues rather than 
introducing negatively affects. I guess, before this commit, cros-ec
always get successful transfer, but the reality is that the tranfer
does failed in the early booting stage but spi-rockchip doesn't log out
anything. If that is the case, that means spi-rockchip fails to prepare
sg for some unknown reasons?

> Reverting the patch silences the cros-ec again. I'll try to look into it
> further, but maybe you also have an idea what might go wrong.
>
>
> Heiko
>
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>


-- 
Best Regards
Shawn Lin