From: <Claudiu.Beznea@microchip.com>
To: <harinik@xilinx.com>, <andrew@lunn.ch>
Cc: <harini.katakam@xilinx.com>, <Nicolas.Ferre@microchip.com>,
<davem@davemloft.net>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <michal.simek@xilinx.com>,
<shubhrajyoti.datta@xilinx.com>, <sai.pavan.boddu@xilinx.com>
Subject: Re: [PATCH v2 1/4] net: macb: Check MDIO state before read/write and use timeouts
Date: Tue, 27 Nov 2018 10:25:11 +0000 [thread overview]
Message-ID: <74937246-dc7d-db1c-df00-5db856192eac@microchip.com> (raw)
In-Reply-To: <CAFcVECK=4e-+1u3X+OuLoAEicUtrkTX3C0wzAugMRcJSP0N-Vg@mail.gmail.com>
Hi Andrew, Harini,
On 27.11.2018 07:36, Harini Katakam wrote:
> Hi Claudiu,
> On Mon, Nov 26, 2018 at 8:22 PM Andrew Lunn <andrew@lunn.ch> wrote:
>>
>> On Mon, Nov 26, 2018 at 02:46:01PM +0000, Claudiu.Beznea@microchip.com wrote:
>>> Hi Harini,
>>>
>>> On 26.11.2018 09:07, Harini Katakam wrote:
>>>> From: Harini Katakam <harinik@xilinx.com>
>>>>
>>>> Replace the while loop in MDIO read/write functions with a timeout.
>>>> In addition, add a check for MDIO bus busy before initiating a new
>>>> operation as well to make sure there is no ongoing MDIO operation.
>>>
>>> Is this MDIO bus busy check necessary? The caller of
>>> macb_mdio_read/macb_mdio_write locks the mdio bus mutex before calling it
>>> (e.g. mdiobus_read).
>>
>> Hi Claudiu
>>
>> It depends on the implementation. A write operation you could just
>> launch, but not wait for it to complete, allowing you to do other
>> stuff while the hardware is busy. For the next operation you then do
>> need to check the previous operation has completed.
>>
>> I've not checked it is actually implemented this way.
>
> Yes, as Andrew mentioned, a previous MDIO bus operation cannot
> be assumed to be complete always - for ex., in case of a timeout.
> There is a chance that the MDIO bus bit is busy when mdio_read/write
> is called.
Thank you for your responses. I see it now.
Then, do you think it would be better to have a new API part of struct
mii_bus that drivers should register so that, the mii core to check if the
bus is idle before lunching a new request?
Thank you,
Claudiu Beznea
>
> Regards,
> Harini
>
next prev parent reply other threads:[~2018-11-27 10:25 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 7:07 [PATCH v2 0/4] Macb power management support for ZynqMP Harini Katakam
2018-11-26 7:07 ` [PATCH v2 1/4] net: macb: Check MDIO state before read/write and use timeouts Harini Katakam
2018-11-26 14:39 ` Andrew Lunn
2018-11-27 5:38 ` Harini Katakam
2018-11-26 14:46 ` Claudiu.Beznea
2018-11-26 14:52 ` Andrew Lunn
2018-11-27 5:36 ` Harini Katakam
2018-11-27 10:25 ` Claudiu.Beznea [this message]
2018-11-27 10:49 ` Harini Katakam
2018-11-28 0:35 ` Andrew Lunn
2018-11-29 10:21 ` Claudiu.Beznea
2018-11-26 7:07 ` [PATCH v2 2/4] net: macb: Support clock management for tsu_clk Harini Katakam
2018-11-26 7:07 ` [PATCH v2 3/4] net: macb: Add pm runtime support Harini Katakam
2018-11-26 14:47 ` Andrew Lunn
2018-11-26 14:47 ` Claudiu.Beznea
2018-11-26 7:07 ` [PATCH v2 4/4] net: macb: Add support for suspend/resume with full power down Harini Katakam
2018-11-26 14:46 ` Claudiu.Beznea
2018-11-27 6:25 ` Harini Katakam
2018-11-27 10:31 ` Claudiu.Beznea
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