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

[Dinh Nguyen <dinguyen@kernel.org>]

On 2/22/22 12:30, Marek Vasut wrote:
> 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.

Hmm...I just tested v5.17-rc3 on a C5 board and QSPI looks to be working 
fine:

[    1.744489] spi-nor spi1.0: found n25q512ax3, expected mt25qu02g
[    1.750534] dma-pl330 ffe01000.pdma: Reset Channel-0  CS-f FTC-40000
[    1.756941] spi-nor spi1.0: n25q512ax3 (65536 Kbytes)
[    1.762369] 2 fixed-partitions partitions found on MTD device 
ff705000.spi.0
[    1.769425] Creating 2 MTD partitions on "ff705000.spi.0":
[    1.774925] 0x000000000000-0x000000800000 : "Flash 0 Raw Data"
[    1.781942] 0x000000800000-0x000008000000 : "Flash 0 jffs2 Filesystem"
[    1.788468] mtd: partition "Flash 0 jffs2 Filesystem" extends beyond 
the end of device "ff705000.spi.0" -- size truncated to 0x3800000

Dinh