Re: [PATCH] mos6522: remove anh register

From: Laurent Vivier <laurent@vivier.eu>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
	qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH] mos6522: remove anh register
Date: Fri, 13 Dec 2019 09:45:09 +0100	[thread overview]
Message-ID: <68431265-fd33-89de-6a61-0c823beaa16e@vivier.eu> (raw)
In-Reply-To: <20191213014419.GA207300@umbus.fritz.box>

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Le 13/12/2019 à 02:44, David Gibson a écrit :
> On Thu, Dec 12, 2019 at 08:43:59PM +0100, Laurent Vivier wrote:
>> Register addr 1 is defined as buffer A with handshake (vBufAH),
>> register addr 15 is also defined as buffer A without handshake (vBufA).
>>
>> Linux kernel has a big "DON'T USE!" next to the register 1 addr
>> definition (vBufAH), and only uses register 15 (vBufA).
>>
>> So remove the definition of 'anh' and use only 'a' (with VIA_REG_ANH and
>> VIA_REG_A).
> 
> I'm not actually following the rationale for removing the register.
> Linux doesn't use it, but if it's part of the real hardware model we
> should keep it, no?

It's actually two methods to access the same register (with handshake,
without handshake).

In the datashit Register 15 is described as "Same as register 1 except
no handshake".

Thanks,
Laurent

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