[PATCH] media: imx-jpeg: Add support for descriptor allocation from SRAM

[Marek Vasut]

On 8/21/25 11:42 AM, Ming Qian(OSS) wrote:

Hello Ming,

>>> Using sram instead of dram only improves timing, but doesn't 
>>> completely circumvent the hardware bug
>> Does it make sense to upstream this patch anyway ?
> 
> I think this patch is helpful.
> 
> But so far, we don't have any SRAM resources for jpeg.
> The i.MX95 does have sram, but it is very limited, and it has been
> assigned to arm_scmi and VPU.

I found out the SM can work fine with only 192 kiB of SRAM instead of 
256 kiB of SRAM. That frees up 64 kiB of SRAM for NS world. Each JPEG IP 
needs 20544 Bytes for descriptors, which fits into those freed up 64 kiB 
of SRAM.

The alternative would be to handle those AXI read errors and restart the 
encoding. I always observe these errors in the CONFIG phase of encoding. 
Do you happen to have any details of this issue you could share ? Do you 
know whether the problem occurs only during CONFIG phase, or also during 
image read phase ?

If the problem occurs only during CONFIG phase of encoding, it would be 
easy to retrigger the CONFIG I think. If the problem occurs also during 
image read, that might need some more creative fix.

> This patch makes the jpeg can support SRAM. Maybe in some scenarios, we
> can assign the SRAM to jpeg instead of VPU.
> 
> So for me, I welcome this patch.

Thank you

-- 
Best regards,
Marek Vasut