Re: [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@xxxxxxxx>
> > Sent: Wednesday, June 21, 2023 4:57 PM
> > To: netdev@xxxxxxxxxxxxxxx
> > Cc: Maxim Kochetkov <fido_max@xxxxxxxx>; Pandey, Radhey Shyam
> > <radhey.shyam.pandey@xxxxxxx>; David S. Miller
> > <davem@xxxxxxxxxxxxx>; Eric Dumazet <edumazet@xxxxxxxxxx>; Jakub
> > Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; Simek,
> > Michal <michal.simek@xxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> > linux-kernel@xxxxxxxxxxxxxxx
> > 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.