[PATCH net] Revert "net: stmmac: Specify hardware capability value when FIFO size isn't specified"

[Paolo Abeni]

On 2/6/25 11:47 AM, Russell King (Oracle) wrote:
> On Thu, Feb 06, 2025 at 09:08:10AM +0100, Paolo Abeni wrote:
>> On 2/5/25 1:57 PM, Russell King (Oracle) wrote:
>>> This reverts commit 8865d22656b4, which caused breakage for platforms
>>> which are not using xgmac2 or gmac4. Only these two cores have the
>>> capability of providing the FIFO sizes from hardware capability fields
>>> (which are provided in priv->dma_cap.[tr]x_fifo_size.)
>>>
>>> All other cores can not, which results in these two fields containing
>>> zero. We also have platforms that do not provide a value in
>>> priv->plat->[tr]x_fifo_size, resulting in these also being zero.
>>>
>>> This causes the new tests introduced by the reverted commit to fail,
>>> and produce e.g.:
>>>
>>> 	stmmaceth f0804000.eth: Can't specify Rx FIFO size
>>>
>>> An example of such a platform which fails is QEMU's npcm750-evb.
>>> This uses dwmac1000 which, as noted above, does not have the capability
>>> to provide the FIFO sizes from hardware.
>>>
>>> Therefore, revert the commit to maintain compatibility with the way
>>> the driver used to work.
>>>
>>> Reported-by: Guenter Roeck <linux at roeck-us.net>
>>> Link: https://lore.kernel.org/r/4e98f967-f636-46fb-9eca-d383b9495b86@roeck-us.net
>>> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
>>
>> Given the fallout caused by the blamed commit, the imminent net PR, and
>> the substantial agreement about the patch already shared by many persons
>> on the ML, unless someone raises very serious concerns very soon, I'm
>> going to apply this patch (a little) earlier than the 24h grace period,
>> to fit the mentioned PR.
> 
> Thanks. Here's the missing Fixes tag that I missed:
> 
> Fixes: 8865d22656b4 ("net: stmmac: Specify hardware capability value when
> FIFO size isn't specified")
> 
> Not sure if patchwork will pick that up.

Thank you indeed for the missing piece. I'll add that when applying the
patch (~now).

/P