Re: [PATCH] [RFC] spi: cadence-quadspi: Disable DAC on SoCFPGA

[Marek Vasut <marex@denx.de>]

On 2/22/22 16:49, Dinh Nguyen wrote:
> 
> 
> On 2/21/22 11:05, Marek Vasut wrote:
>> On 2/21/22 17:38, Dinh Nguyen wrote:
>>>
>>>
>>> On 2/20/22 22:32, Marek Vasut wrote:
>>>> On SoCFPGA Gen5, DAC memcpy_fromio() in cqspi_direct_read_execute()
>>>> leads to data abort, disable DAC to avoid triggering it:
>>>>
>>>> Unhandled fault: imprecise external abort (0x1406) at 0x0400d3e9
>>>> [0400d3e9] *pgd=00000000
>>>>
>>>> Signed-off-by: Marek Vasut <marex@denx.de>
>>>> Cc: Dinh Nguyen <dinguyen@kernel.org>
>>>> Cc: Pratyush Yadav <p.yadav@ti.com>
>>>> ---
>>>>   drivers/spi/spi-cadence-quadspi.c | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/spi/spi-cadence-quadspi.c 
>>>> b/drivers/spi/spi-cadence-quadspi.c
>>>> index b808c94641fa6..65f2c2449be09 100644
>>>> --- a/drivers/spi/spi-cadence-quadspi.c
>>>> +++ b/drivers/spi/spi-cadence-quadspi.c
>>>> @@ -1870,7 +1870,7 @@ static const struct cqspi_driver_platdata 
>>>> intel_lgm_qspi = {
>>>>   };
>>>>   static const struct cqspi_driver_platdata socfpga_qspi = {
>>>> -    .quirks = CQSPI_NO_SUPPORT_WR_COMPLETION,
>>>> +    .quirks = CQSPI_DISABLE_DAC_MODE | CQSPI_NO_SUPPORT_WR_COMPLETION,
>>>>   };
>>>>   static const struct cqspi_driver_platdata versal_ospi = {
>>>
>>> Acked-by: Dinh Nguyen <dinguyen@kernel.org>
>>
>> Is this DAC really not working on socfpga gen5 or is there some other 
>> issue ?
> 
> I don't know the answer to this question. What is the DAC in the QSPI 
> module and how do I go about testing it?

DAC = direct access.

How do you go about testing this -- compile kernel with/without this 
patch, boot on SoCFPGA Gen5 with QSPI NOR attached, the kernel crashes 
without this patch on imprecise external abort.