netdev - Re: [PATCH 3/4] net: mvneta: mmc: get optional axi clk

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Date:	Wed, 20 Jan 2016 12:03:03 +0100
From:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To:	Jisheng Zhang <jszhang@...vell.com>
Cc:	thomas.petazzoni@...e-electrons.com, davem@...emloft.net,
	mw@...ihalf.com, robh+dt@...nel.org, pawel.moll@....com,
	mark.rutland@....com, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, devicetree@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/4] net: mvneta: mmc: get optional axi clk

On 01/20/2016 10:42 AM, Jisheng Zhang wrote:
> On Wed, 20 Jan 2016 10:31:18 +0100 Sebastian Hesselbarth  wrote:
>
>> On January 20, 2016 9:15:22 AM Jisheng Zhang wrote:
>>
>>> Some platforms may provide more than one clk for the mvneta IP, for
>>> example Marvell BG4CT provides "core" clk for the mac core, and
>>> "axi" clk for the AXI bus logic. Obviously this "axi" clk also need to
>>> be enabled. This patch adds this optional "axi" clk support.
>>
>> Jisheng,
>>
>> although I do not expect mvneta to appear on a non-AXI bus
>> anytime soon, how about naming the clock "bus" instead?
>
> Good question. IIRC, this IP expects AXI bus, but I'll check with HW people.

Actually, I am quite sure the current IP requires AXI. But my comment
was more about to make the binding a little bit more flexible to
_future_ variants/SoCs we may stumble upon.

Naming the clock "bus" or "dma" will work for the current _and_ future
IPs, while "axi" may not.

Sebastian

>>
>> If you know the clock is only required for bus master DMA but
>> not for register access, "dma" would be an even better name.
>>
>> Sebastian
>>
>>
>>> Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
>>> ---
>>>   drivers/net/ethernet/marvell/mvneta.c | 8 ++++++++
>>>   1 file changed, 8 insertions(+)
>>>
>>> diff --git a/drivers/net/ethernet/marvell/mvneta.c
>>> b/drivers/net/ethernet/marvell/mvneta.c
>>> index aca0a73..6bb709a 100644
>>> --- a/drivers/net/ethernet/marvell/mvneta.c
>>> +++ b/drivers/net/ethernet/marvell/mvneta.c
>>> @@ -373,6 +373,8 @@ struct mvneta_port {
>>>
>>>   	/* Core clock */
>>>   	struct clk *clk;
>>> +	/* AXI clock */
>>> +	struct clk *clk_axi;
>>>   	u8 mcast_count[256];
>>>   	u16 tx_ring_size;
>>>   	u16 rx_ring_size;
>>> @@ -3615,6 +3617,10 @@ static int mvneta_probe(struct platform_device *pdev)
>>>
>>>   	clk_prepare_enable(pp->clk);
>>>
>>> +	pp->clk_axi = devm_clk_get(&pdev->dev, "axi");
>>> +	if (!IS_ERR(pp->clk_axi))
>>> +		clk_prepare_enable(pp->clk_axi);
>>> +
>>>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>   	pp->base = devm_ioremap_resource(&pdev->dev, res);
>>>   	if (IS_ERR(pp->base)) {
>>> @@ -3727,6 +3733,7 @@ err_free_ports:
>>>   	free_percpu(pp->ports);
>>>   err_clk:
>>>   	clk_disable_unprepare(pp->clk);
>>> +	clk_disable_unprepare(pp->clk_axi);
>>>   err_put_phy_node:
>>>   	of_node_put(phy_node);
>>>   err_free_irq:
>>> @@ -3744,6 +3751,7 @@ static int mvneta_remove(struct platform_device *pdev)
>>>
>>>   	unregister_netdev(dev);
>>>   	clk_disable_unprepare(pp->clk);
>>> +	clk_disable_unprepare(pp->clk_axi);
>>>   	free_percpu(pp->ports);
>>>   	free_percpu(pp->stats);
>>>   	irq_dispose_mapping(dev->irq);
>>> --
>>> 2.7.0.rc3
>>>
>>
>>
>