RE: [PATCH net] Revert "net: stmmac: platform: Fix MDIO init for platforms without PHY"

From: "Sriram Dash" <sriram.dash@samsung.com>
To: "'Florian Fainelli'" <f.fainelli@gmail.com>, <netdev@vger.kernel.org>
Cc: 'Jose Abreu' <Jose.Abreu@synopsys.com>,
	'Jayati Sahu' <jayati.sahu@samsung.com>,
	'Alexandre Torgue' <alexandre.torgue@st.com>,
	tomeu.vizoso@collabora.com, rcsekar@samsung.com,
	khilman@baylibre.com, mgalka@collabora.com,
	linux-kernel@vger.kernel.org,
	'Padmanabhan Rajanbabu' <p.rajanbabu@samsung.com>,
	linux-stm32@st-md-mailman.stormreply.com, broonie@kernel.org,
	pankaj.dubey@samsung.com,
	'Maxime Coquelin' <mcoquelin.stm32@gmail.com>,
	guillaume.tucker@collabora.com, enric.balletbo@collabora.com,
	'Giuseppe Cavallaro' <peppe.cavallaro@st.com>,
	"'David S. Miller'" <davem@davemloft.net>,
	linux-arm-kernel@lists.infradead.org, heiko@sntech.de
Subject: RE: [PATCH net] Revert "net: stmmac: platform: Fix MDIO init for platforms without PHY"
Date: Tue, 7 Jan 2020 11:16:36 +0530	[thread overview]
Message-ID: <011a01d5c51d$d7482290$85d867b0$@samsung.com> (raw)
In-Reply-To: <20200107050846.16838-1-f.fainelli@gmail.com>

> From: Florian Fainelli <f.fainelli@gmail.com>
> Subject: [PATCH net] Revert "net: stmmac: platform: Fix MDIO init for
platforms
> without PHY"
> 
> This reverts commit d3e014ec7d5ebe9644b5486bc530b91e62bbf624 ("net:
> stmmac: platform: Fix MDIO init for platforms without PHY") because it
breaks
> existing systems with stmmac which do not have a MDIO bus sub-node nor a
> 'phy-handle' property declared in their Device Tree. On those systems, the
> stmmac MDIO bus is expected to be created and then scanned by
> of_mdiobus_register() to create PHY devices.
> 
> While these systems should arguably make use of a more accurate Device
Tree
> reprensentation with the use of the MDIO bus sub-node an appropriate 'phy-
> handle', we cannot break them, therefore restore the behavior prior to the
said
> commit.
> 
> Fixes: d3e014ec7d5e ("net: stmmac: platform: Fix MDIO init for platforms
> without PHY")
> Reported-by: Heiko Stuebner <heiko@sntech.de>
> Reported-by: kernelci.org bot <bot@kernelci.org>
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Nacked-by: Sriram Dash <Sriram.dash@samsung.com>

> ---
> Heiko,
> 
> I did not add the Tested-by because the patch is a little bit different
from what
> you tested, even if you most likely were not hitting the other part that I
was
> changing. Thanks!
> 
>  drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> index cc8d7e7bf9ac..bedaff0c13bd 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> @@ -320,7 +320,7 @@ static int stmmac_mtl_setup(struct platform_device
> *pdev,  static int stmmac_dt_phy(struct plat_stmmacenet_data *plat,
>  			 struct device_node *np, struct device *dev)  {
> -	bool mdio = false;
> +	bool mdio = true;

This is breaking for the platforms with fixed-link.
stih418-b2199.dts and 169445.dts to name a few.

For the newer platforms, they should provide the mdio/ snps,dwmac-mdio
property in the device tree as we are checking the mdio/ snps,dwmac-mdio
property in the stmmac_platform driver for the mdio bus memory allocation.
For existing platforms, I agree we should not break them, but we should make
the code correct. And make the existing platforms adapt to the proper code.
There is a proposed solution. 
https://lkml.org/lkml/2020/1/7/14

What do you think?

>  	static const struct of_device_id need_mdio_ids[] = {
>  		{ .compatible = "snps,dwc-qos-ethernet-4.10" },
>  		{},
> --
> 2.19.1

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