On Wed, Feb 05, 2025 at 12:13:59AM +0800, Chen-Yu Tsai wrote:
> From: Chen-Yu Tsai <wens@xxxxxxxx>
>
> The DWMAC 1000 DMA capabilities register does not provide actual
> FIFO sizes, nor does the driver really care. If they are not
> provided via some other means, the driver will work fine, only
> disallowing changing the MTU setting.
>
> The recent commit 8865d22656b4 ("net: stmmac: Specify hardware
> capability value when FIFO size isn't specified") changed this by
> requiring the FIFO sizes to be provided, breaking devices that were
> working just fine.
>
> Provide the FIFO sizes through the driver's platform data, to not
> only fix the breakage, but also enable MTU changes. The FIFO sizes
> are confirmed to be the same across RK3288, RK3328, RK3399 and PX30,
> based on their respective manuals. It is likely that Rockchip
> synthesized their DWMAC 1000 with the same parameters on all their
> chips that have it.
>
> Fixes: eaf4fac47807 ("net: stmmac: Do not accept invalid MTU values")
> Fixes: 8865d22656b4 ("net: stmmac: Specify hardware capability value when FIFO size isn't specified")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
> ---
> The reason for stable inclusion is not to fix the device breakage
> (which only broke in v6.14-rc1), but to provide the values so that MTU
> changes can work in older kernels.
Allowing the MTU to be changed is probably classed as a new feature,
not bug fix.
I _think_ this also allows flow control, which again is a new feature.
Please submit to net-next.
Andrew
