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From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, qemu-devel@nongnu.org
Cc: Jason Wang <jasowang@redhat.com>,
	Laurent Vivier <laurent@vivier.eu>,
	Finn Thain <fthain@linux-m68k.org>
Subject: Re: [PATCH 2/6] dp8393x: don't force 32-bit register access
Date: Sat, 3 Jul 2021 18:29:12 +0200	[thread overview]
Message-ID: <6fb1c380-1a0c-9d0e-be20-b2a7baec3f51@amsat.org> (raw)
In-Reply-To: <88ef2d9c-7dcb-2e2e-037c-6af306ad2a12@ilande.co.uk>

On 7/3/21 4:39 PM, Mark Cave-Ayland wrote:
> On 03/07/2021 15:19, Philippe Mathieu-Daudé wrote:
> 
>> From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>
>> Commit 3fe9a838ec "dp8393x: Always use 32-bit accesses" assumed that
>> all accesses
>> to the registers were 32-bit but this is actually not the case. The
>> access size is
>> determined by the CPU instruction used and not the number of physical
>> address lines.
>>
>> The big_endian workaround applied to the register read/writes was
>> actually caused
>> by forcing the access size to 32-bit when the guest OS was using a
>> 16-bit access.
>> Since the registers are 16-bit then we can simply set .impl.min_access
>> to 2 and
>> then the memory API will automatically do the right thing for both
>> 16-bit accesses
>> used by Linux and 32-bit accesses used by the MacOS toolbox ROM.
> 
> The change should work, but the commit message above needs a slight
> tweak - maybe something like this?
> 
> Since the registers are 16-bit then we can simply set both
> .impl.min_access and .impl.max_access to 2 and then the memory API will
> automatically do the right thing for both 16-bit accesses used by Linux
> and 32-bit accesses used by the MacOS toolbox ROM.

Do you mind sending v3 of this patch reworded (and including the .valid
fields)?

>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>> Fixes: 3fe9a838ec ("dp8393x: Always use 32-bit accesses")
>> Tested-by: Finn Thain <fthain@linux-m68k.org>
>> Message-Id: <20210625065401.30170-9-mark.cave-ayland@ilande.co.uk>
>> [PMD: dp8393x_ops.impl.max_access_size 4 -> 2]
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>   hw/net/dp8393x.c | 9 ++++-----
>>   1 file changed, 4 insertions(+), 5 deletions(-)


  reply	other threads:[~2021-07-03 16:29 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-03 14:19 [RFC PATCH 0/6] dp8393x: Housekeeping Philippe Mathieu-Daudé
2021-07-03 14:19 ` [PATCH 1/6] dp8393x: fix CAM descriptor entry index Philippe Mathieu-Daudé
2021-07-03 14:19 ` [PATCH 2/6] dp8393x: don't force 32-bit register access Philippe Mathieu-Daudé
2021-07-03 14:39   ` Mark Cave-Ayland
2021-07-03 16:29     ` Philippe Mathieu-Daudé [this message]
2021-07-04 15:34       ` Mark Cave-Ayland
2021-07-04  2:06   ` Finn Thain
2021-07-03 14:19 ` [RFC PATCH 3/6] dp8393x: Restrict bus access to 16/32-bit operations Philippe Mathieu-Daudé
2021-07-03 14:52   ` Mark Cave-Ayland
2021-07-04 14:45   ` Mark Cave-Ayland
2021-07-03 14:19 ` [RFC PATCH 4/6] dp8393x: Store CAM registers as 16-bit Philippe Mathieu-Daudé
2021-07-03 14:56   ` Mark Cave-Ayland
2021-07-04 14:48   ` Mark Cave-Ayland
2021-07-06 17:29     ` Philippe Mathieu-Daudé
2021-07-06 19:27       ` Mark Cave-Ayland
2021-07-03 14:19 ` [PATCH 5/6] dp8393x: Replace address_space_rw(is_write=1) by address_space_write() Philippe Mathieu-Daudé
2021-07-03 14:57   ` Mark Cave-Ayland
2021-07-04 14:49   ` Mark Cave-Ayland
2021-07-03 14:19 ` [RFC PATCH 6/6] dp8393x: Rewrite dp8393x_get() / dp8393x_put() Philippe Mathieu-Daudé
2021-07-03 15:00   ` Mark Cave-Ayland
2021-07-03 15:04     ` Philippe Mathieu-Daudé
2021-07-04  1:46   ` Finn Thain
2021-07-04 15:07   ` Mark Cave-Ayland
2021-07-05  1:36     ` Finn Thain
2021-07-05  6:34       ` Mark Cave-Ayland
2021-07-07  1:30         ` Finn Thain
2021-07-07 10:12           ` Mark Cave-Ayland
2021-07-09  9:13             ` Finn Thain

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