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Re: [PATCH for-6.2 0/2] escc: fixes for STATUS_TXEMPTY and SPEC_ALLSENT

From: Peter Maydell
Subject: Re: [PATCH for-6.2 0/2] escc: fixes for STATUS_TXEMPTY and SPEC_ALLSENT
Date: Thu, 18 Nov 2021 18:23:38 +0000

On Thu, 18 Nov 2021 at 18:18, Mark Cave-Ayland
<mark.cave-ayland@ilande.co.uk> wrote:
> This is another attempt to fix booting 32-bit QEMU SPARC machines in
> qemu-system-sparc using a real Sun PROM based upon further experiments and
> re-reading of the ESCC datasheet from a previous patch posted at
> https://lists.gnu.org/archive/html/qemu-devel/2021-11/msg00324.html.
> It appears that both the Sun PROM and OpenBSD with OpenBIOS fail to send an
> explicit reset command as recommended in the ESCC datasheet, which causes
> hangs during serial port enumeration since the introduction of the recent
> ESCC reset changes.
> The first patch always sets STATUS_TXEMPTY in R_STATUS on hardware reset
> which wasn't documented in the "Reset" section(s) but is documented in the
> "Transmit Interrupts and Transmit Buffer Empty Bit" section, whilst the
> second patch updates SPEC_ALLSENT when writing to W_TXCTRL1.
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

-- PMM

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