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Re: [SPAM] [RFC PATCH v42 90/98] hw/sd/sdcard: Add experimental 'x-aspee


From: Philippe Mathieu-Daudé
Subject: Re: [SPAM] [RFC PATCH v42 90/98] hw/sd/sdcard: Add experimental 'x-aspeed-emmc-kludge' property
Date: Tue, 2 Jul 2024 22:05:29 +0200
User-agent: Mozilla Thunderbird

On 2/7/24 18:21, Cédric Le Goater wrote:
On 7/2/24 6:15 PM, Philippe Mathieu-Daudé wrote:
On 2/7/24 07:06, Andrew Jeffery wrote:
On Fri, 2024-06-28 at 11:16 +0200, Cédric Le Goater wrote:
On 6/28/24 9:02 AM, Philippe Mathieu-Daudé wrote:
When booting U-boot/Linux on Aspeed boards via eMMC,
some commands don't behave as expected from the spec.

Add the 'x-aspeed-emmc-kludge' property to allow non
standard uses until we figure out the reasons.

I am not aware of any singularity in the eMMC logic provided by Aspeed.
U-Boot and Linux drivers seem very generic. May be others can tell.

I'm not aware of any command kludges. The main problem I had when I
wrote the Linux driver for the Aspeed controller was the phase tuning,
but that doesn't sound related.

Yeah I don't think anything Aspeed nor U-boot related, we
model CSD/CID registers per the SD spec, not MMC. Various
fields are identical, but few differ, this might be the
problem.

I rather respect the spec by default, so until we figure
the issue, are you OK to use a 'x-emmc-kludge' property
and set it on the Aspeed boards?

If these differences are eMMC related, why not simply test :

     if (sd_is_emmc(sd)) ...

in commands ALL_SEND_CID and APP_CMD ? The extra property looks
ambiguous to me.

I'd like to keep the sd_is_emmc() check for code respecting
the eMMC spec. I believe the commands in sd_proto_emmc[] in
this series do respect it, modulo some register field
definitions that are SD specific. So 'x-emmc-kludge' would
be a property to allow eMMC use -- without delaying it further
--, by bypassing a *bug* in our current model. I'm willing to
figure out the problem and fix it, but /after/ the 9.1 release.
We are too close of the soft freeze and trying to fix that
before is too much pressure on my right now.

Thanks,

C.






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