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Message-ID: <0273daf8-7eeb-17bc-2246-6b29ae27a99d@inbox.ru>
Date:   Wed, 21 Jun 2023 16:10:06 +0300
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Subject: Re: [PATCH 1/1] net: axienet: Move reset before DMA detection
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To:     "Pandey, Radhey Shyam" <radhey.shyam.pandey@amd.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "Simek, Michal" <michal.simek@amd.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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From:   Maxim Kochetkov <fido_max@inbox.ru>
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On 21.06.2023 15:23, Pandey, Radhey Shyam wrote:
>> -----Original Message-----
>> From: Maxim Kochetkov <fido_max@inbox.ru>
>> Sent: Wednesday, June 21, 2023 4:57 PM
>> To: netdev@vger.kernel.org
>> Cc: Maxim Kochetkov <fido_max@inbox.ru>; Pandey, Radhey Shyam
>> <radhey.shyam.pandey@amd.com>; David S. Miller
>> <davem@davemloft.net>; Eric Dumazet <edumazet@google.com>; Jakub
>> Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>; Simek,
>> Michal <michal.simek@amd.com>; linux-arm-kernel@lists.infradead.org;
>> linux-kernel@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.