Re: [PATCH v3 2/9] net: arc_emac: add phy reset is optional for device tree

From: Caesar Wang <caesar.upstream@gmail.com>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: Caesar Wang <wxt@rock-chips.com>,
	Heiko Stuebner <heiko@sntech.de>,
	"David S. Miller" <davem@davemloft.net>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org, Pawel Moll <pawel.moll@arm.com>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	netdev@vger.kernel.org, Kumar Gala <galak@codeaurora.org>,
	linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org,
	keescook@google.com, leozwang@google.com
Subject: Re: [PATCH v3 2/9] net: arc_emac: add phy reset is optional for device tree
Date: Thu, 17 Mar 2016 18:02:47 +0800	[thread overview]
Message-ID: <56EA80C7.30303@gmail.com> (raw)
In-Reply-To: <56E96656.5000101@cogentembedded.com>

Hi Sergei,

在 2016年03月16日 21:57, Sergei Shtylyov 写道:
> Hello.
>
> On 3/14/2016 11:01 AM, Caesar Wang wrote:
>
>> This patch adds the following property for arc_emac.
>>
>> 1) phy-reset-gpios:
>> The phy-reset-gpio is an optional property for arc emac device tree 
>> boot.
>> Change the binding document to match the driver code.
>>
>> 2) phy-reset-duration:
>> Different boards may require different phy reset duration. Add property
>> phy-reset-duration for device tree probe, so that the boards that need
>> a longer reset duration can specify it in their device tree.
>>
>> Anyway, we can add the above property for arc emac.
>>
>> Signed-off-by: Caesar Wang <wxt@rock-chips.com>
>
>   Could you have a look at drivers/net/ethernet/cadence/macb/? It 
> seems to be the only driver which places the PHY's "reset-gpios" prop 
> correctly, into the PHY subnode? I'm currently working on adding 
> support of this prop into phylib...

I see the driver on now.

     /* Power up the PHY if there is a GPIO reset */
     phy_node =  of_get_next_available_child(np, NULL);
     if (phy_node) {
         int gpio = of_get_named_gpio(phy_node, "reset-gpios", 0);
         if (gpio_is_valid(gpio))
             bp->reset_gpio = gpio_to_desc(gpio);
         gpiod_set_value(bp->reset_gpio, GPIOD_OUT_HIGH);
     }
     of_node_put(phy_node);
...

Frankly, I don't like this way in device drivers.
That's seem same with the /drivers/mmc/core/pwrseq_simple.c,  power up 
the device.
Is it not really reset hardware PHY from the gpio reset pin?  Just power up.

Of course, I hope to see and test it if you improve the PHY framework to 
support the phy reset.:-)

---

Anyway,  David had applied this series patches into net branch.

Although the clock and dts patches should be applied into Heiko branch,  
I'm glad to see David's way.

Heiko branch:
https://git.kernel.org/cgit/linux/kernel/git/mmind/linux-rockchip.git/

I wish won't destory Heiko to merge in the future.

-Caesar

>
> MBR, Sergei
>
>
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-- 
Thanks,
Caesar