[PATCH 1/1] net: axienet: Move reset before DMA detection

[Maxim Kochetkov]

On 21.06.2023 15:23, Pandey, Radhey Shyam wrote:
>> -----Original Message-----
>> From: Maxim Kochetkov <fido_max at inbox.ru>
>> Sent: Wednesday, June 21, 2023 4:57 PM
>> To: netdev at vger.kernel.org
>> Cc: Maxim Kochetkov <fido_max at inbox.ru>; Pandey, Radhey Shyam
>> <radhey.shyam.pandey at amd.com>; David S. Miller
>> <davem at davemloft.net>; Eric Dumazet <edumazet at google.com>; Jakub
>> Kicinski <kuba at kernel.org>; Paolo Abeni <pabeni at redhat.com>; Simek,
>> Michal <michal.simek at amd.com>; linux-arm-kernel at lists.infradead.org;
>> linux-kernel at vger.kernel.org
>> Subject: [PATCH 1/1] net: axienet: Move reset before DMA detection
>>
>> DMA detection will fail if axinet was started before (by boot loader, boot
>> ROM, etc). In this state axinet will not start properly.
>> So move axinet reset before DMA detection.
> 
> Please provide more detail on the failing testcase. In which scenario we are
> seeing DMA detection failure? What is error log . Is it random?
> 

XAXIDMA_TX_CDESC_OFFSET + 4 register (MM2S_CURDESC_MSB) is used to 
detect 64 DMA capability here. But datasheet says: When DMACR.RS is 1 
(axinet is in enabled state), CURDESC_PTR becomes Read Only (RO) and is 
used to fetch the first
descriptor. So iowrite32()/ioread32() trick to this register is failed.