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Re: [PATCH v2 30/42] esp: add 4 byte PDMA read and write transfers


From: Philippe Mathieu-Daudé
Subject: Re: [PATCH v2 30/42] esp: add 4 byte PDMA read and write transfers
Date: Tue, 16 Feb 2021 08:30:32 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0

Hi Mark,

On 2/15/21 11:35 PM, Mark Cave-Ayland wrote:
> On 12/02/2021 18:56, Philippe Mathieu-Daudé wrote:
> 
>> On 2/9/21 8:30 PM, Mark Cave-Ayland wrote:
>>> The MacOS toolbox ROM performs 4 byte reads/writes when transferring
>>> data to
>>> and from the target. Since the SCSI bus is 16-bits wide, use the
>>> memory API
>>> to split a 4 byte access into 2 x 2 byte accesses.
>>>
>>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>> ---
>>>   hw/scsi/esp.c | 6 ++++--
>>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>>
>> Out of curiosity, what is the bus used?
> 
> AFAICT it's a custom logic chip that sits on the CPU address/data buses
> that does the decoding between the CPU and ESP chip. Other than a simple
> block diagram of the Quadra there isn't much official documentation out
> there :/

OK.

> Are you planning to review any more of this series? I'm keen to put out
> a (hopefully final) v3 soon, but I'll hold off for little while if you
> want more time to look over the remaining patches.

I talked about this series with Laurent on Sunday, asking him for
review help ;) I don't remember if there is any big comment to
address in patches 1-14. If not I can review the missing ones
there today and you could send directly a pull request for this
first set, then send the rest as v3. Does that help?
For the rest I doubt having time to focus before Friday.

Regards,

Phil.



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