Re: [PATCH] hw/arm/armv7m: Handle disconnected clock inputs

[Richard Henderson <richard.henderson@linaro.org>]

On 2/9/22 04:16, Peter Maydell wrote:
> In the armv7m object, handle clock inputs that aren't connected.
> This is always an error for 'cpuclk'. For 'refclk' it is OK for this
> to be disconnected, but we need to handle it by not trying to connect
> a sourceless-clock to the systick device.
> 
> This fixes a bug where on the mps2-an521 and similar boards (which
> do not have a refclk) the systick device incorrectly reset with
> SYST_CSR.CLKSOURCE 0 ("use refclk") rather than 1 ("use CPU clock").
> 
> Cc:qemu-stable@nongnu.org
> Reported-by: Richard Petri<git@rpls.de>
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
> The other option would be to have clock_has_source() look not
> just at clk->source but somehow walk up the clock tree to see
> if it can find something that looks like a "root". That seems
> overcomplicated...
> ---
>   hw/arm/armv7m.c | 26 ++++++++++++++++++++++----
>   1 file changed, 22 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~