Re: [PATCH net-next v2 0/9] Add support for OPEN Alliance 10BASE-T1x MACPHY Serial Interface

From: <Parthiban.Veerasooran@microchip.com>
To: <andrew@lunn.ch>
Cc: <benjamin@bigler.one>, <netdev@vger.kernel.org>,
	<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-doc@vger.kernel.org>, <Horatiu.Vultur@microchip.com>,
	<Woojung.Huh@microchip.com>, <Nicolas.Ferre@microchip.com>,
	<UNGLinuxDriver@microchip.com>,
	<Thorsten.Kummermehr@microchip.com>, <davem@davemloft.net>,
	<edumazet@google.com>, <kuba@kernel.org>, <pabeni@redhat.com>,
	<robh+dt@kernel.org>, <krzysztof.kozlowski+dt@linaro.org>,
	<conor+dt@kernel.org>, <corbet@lwn.net>,
	<Steen.Hegelund@microchip.com>, <rdunlap@infradead.org>,
	<horms@kernel.org>, <casper.casan@gmail.com>
Subject: Re: [PATCH net-next v2 0/9] Add support for OPEN Alliance 10BASE-T1x MACPHY Serial Interface
Date: Tue, 26 Mar 2024 09:43:33 +0000	[thread overview]
Message-ID: <cf1cfa86-a12f-437b-a122-8c58ccb01d5f@microchip.com> (raw)
In-Reply-To: <b1e87ca5-f126-4381-a530-75217894cc4a@lunn.ch>

[-- Attachment #1: Type: text/plain, Size: 1960 bytes --]

Hi Andrew,

On 25/03/24 7:31 pm, Andrew Lunn wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
>> It looks like the IRQ is asserted on RESET completion and expects a data
>> chunk from host to deassert the IRQ. I used to test the driver in RPI 4
>> using iperf3. For some reason I never faced this issue, may be when the
>> network device is being registered there might be some packet
>> transmission which leads to deliver a data chunk so that the IRQ is
>> deasserted.
> 
> If you have IPv6 enabled, the network stack will try to add a link
> local IPv6 address to the interface, which means performing a
> Duplicate Address Detection. That means sending a few packets.
> 
> Try disabling IPv6 if you want to reproduce the problem.
Yes, I saw that IPv6 is enabled by default in my RPI 4. So as you 
mentioned, I tried disabling it but still approximately in 1 second 
there is a packet coming from the n/w stack which makes the IRQ 
deasserted (Refer the attached screenshot). So just for testing, I 
disabled waking up the SPI thread from the oa_tc6_start_xmit() function 
and noted that the IRQ is not deasserted throughout the period in Logic 
analyzer.

As I replied in the previous email, using the below code makes the IRQ 
deasserted when the oa_tc6_init() finishes without expecting any data 
chunk from oa_tc6_start_xmit(). So in my opinion let's stick with this 
solution.

/* oa_tc6_sw_reset_macphy() function resets and clears the MAC-PHY reset
  * complete status. IRQ is also asserted on reset completion and it is
  * remain asserted until MAC-PHY receives a data chunk. So performing an
  * empty data chunk transmission will deassert the IRQ. Refer section
  * 7.7 and 9.2.8.8 in the OPEN Alliance specification for more details.
  */
tc6->int_flag = true;
wake_up_interruptible(&tc6->spi_wq);

Best regards,
Parthiban V
> 
>            Andrew

[-- Attachment #2: Screenshot from 2024-03-26 14-12-50.png --]
[-- Type: image/png, Size: 140740 bytes --]