netdev - Re: [PATCH] net: ethernet: stmmac: properly set PS bit in MII configurations during reset

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Date:   Wed, 10 May 2017 09:03:12 +0200
From:   Giuseppe CAVALLARO <peppe.cavallaro@...com>
To:     Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
CC:     Corentin Labbe <clabbe.montjoie@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        <netdev@...r.kernel.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH] net: ethernet: stmmac: properly set PS bit in MII
 configurations during reset

Hi Thomas

On 5/8/2017 9:12 PM, Thomas Petazzoni wrote:
> Hello,
>
> On Mon, 8 May 2017 16:28:21 +0200, Giuseppe CAVALLARO wrote:
>
>>> I just see that GMAC_CONTROL and MAC_CTRL_REG are the same, so why not create a custom adjust_link for each dwmac type ?
>>> This will permit to call it instead of set_ps() and remove lots of if (has_gmac) and co in stmmac_adjust_link()
>>> Basicly replace all between "ctrl = readl()... and writel(ctrl)" by a sot of priv->hw->mac->adjust_link()
>>>
>>> It will also help a lot for my dwmac-sun8i inclusion (since I add some if has_sun8i:))
>> Corentin, I think this is a good idea and maybe necessary now that the
>> driver is supporting a lot of chips.
>> In the past it was sufficient to have a adjust link function and a
>> stmmac_hw_fix_mac_speed
>> to invoke dedicated hook shared between MAC10/100 and GMAC inside STM
>> platforms.
>>
>> Thomas, I wonder if you could take a look at the
>> priv->plat->fix_mac_speed. This can be used
>> for setting internal registers too.
> Once again, this is not called at the right time to fix the issue I'm
> seeing with a MII PHY. I need to adjust the PS bit between asserting the
> reset and polling for the reset bit to clear.
>
> ->fix_mac_speed() is called in the adjust_link() call-back, which is
> called way too late.
>
> Please, read again my patch and the description of the problem that I
> have sent. But basically, any solution that does not allow to set the
> PS bit between asserting the DMA reset bit and polling for it to clear
> will not work for MII PHYs.

yes your point was clear to me, I was just wondering if we could find an 
easier way
to solve it w/o changing the API, adding  the set_ps and propagating the 
"interface"
inside the DMA reset.

Maybe this could be fixed in the glue-logic in some way. Let me know 
what do you think.

peppe

>
> Best regards,
>
> Thomas Petazzoni