Re: [PATCH] hw/input/tsc210x: Don't abort on bad SPI word widths

[Alex Bennée]

Peter Maydell <peter.maydell@linaro.org> writes:

> The tsc210x doesn't support anything other than 16-bit reads on the
> SPI bus, but the guest can program the SPI controller to attempt
> them anyway. If this happens, don't abort QEMU, just log this as
> a guest error.
>
> This fixes our machine_arm_n8x0.py:N8x0Machine.test_n800
> acceptance test, which hits this assertion.
>
> The reason we hit the assertion is because the guest kernel thinks
> there is a TSC2005 on this SPI bus address, not a TSC210x.  (The n810
> *does* have a TSC2005 at this address.) The TSC2005 supports the
> 24-bit accesses which the guest driver makes, and the TSC210x does
> not (that is, our TSC210x emulation is not missing support for a word
> width the hardware can handle).  It's not clear whether the problem
> here is that the guest kernel incorrectly thinks the n800 has the
> same device at this SPI bus address as the n810, or that QEMU's n810
> board model doesn't get the SPI devices right.  At this late date
> there no longer appears to be any reliable information on the web
> about the hardware behaviour, but I am inclined to think this is a
> guest kernel bug.  In any case, we prefer not to abort QEMU for
> guest-triggerable conditions, so logging the error is the right thing
> to do.
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/736
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée