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Message-ID: <63a7f0a7-a634-49a8-8502-abb117b6ca3c@quicinc.com>
Date: Wed, 3 Jan 2024 21:27:03 +0800
From: Jie Luo <quic_luoj@...cinc.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
CC: <agross@...nel.org>, <andersson@...nel.org>, <konrad.dybcio@...aro.org>,
<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
<pabeni@...hat.com>, <robh+dt@...nel.org>,
<krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
<andrew@...n.ch>, <hkallweit1@...il.com>, <robert.marko@...tura.hr>,
<linux-arm-msm@...r.kernel.org>, <netdev@...r.kernel.org>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<quic_srichara@...cinc.com>
Subject: Re: [PATCH v4 1/5] net: mdio: ipq4019: move eth_ldo_rdy before MDIO
bus register
On 1/3/2024 1:24 AM, Russell King (Oracle) wrote:
> On Mon, Dec 25, 2023 at 04:44:20PM +0800, Luo Jie wrote:
>> +/* Maximum SOC PCS(uniphy) number on IPQ platform */
>> +#define ETH_LDO_RDY_CNT 3
>> +
>> struct ipq4019_mdio_data {
>> - void __iomem *membase;
>> - void __iomem *eth_ldo_rdy;
>> + void __iomem *membase;
>> + void __iomem *eth_ldo_rdy[ETH_LDO_RDY_CNT];
>
> Do you have any plans to make use of eth_ldo_rdy other than by code that
> you touch in this patch? If you don't, what is the point of storing
> these points in struct ipq4019_mdio_data ? You're using devm_ioremap()
> which will already store the pointer internally to be able to free the
> resource at the appropriate moment, so if your only use is shortly after
> devm_ioremap(), you can use a local variable for this... meaning this
> becomes (in addition to the other suggestion):
I will remove the eth_lod_rdy from the structure, which is only for
enabling LDO shortly, will update to use the local variable for this.
Thanks for review comments.
>
>> + /* This resource are optional */
>> + for (index = 0; index < ETH_LDO_RDY_CNT; index++) {
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, index + 1);
>> + if (res) {
>> + priv->eth_ldo_rdy[index] = devm_ioremap(&pdev->dev,
>> + res->start,
>> + resource_size(res));
>> +
>> + /* The ethernet LDO enable is necessary to reset PHY
>> + * by GPIO, some PHY(such as qca8084) GPIO reset uses
>> + * the MDIO level reset, so this function should be
>> + * called before the MDIO bus register.
>> + */
>> + if (priv->eth_ldo_rdy[index]) {
>> + u32 val;
>> +
>> + val = readl(priv->eth_ldo_rdy[index]);
>> + val |= BIT(0);
>> + writel(val, priv->eth_ldo_rdy[index]);
>> + fsleep(IPQ_PHY_SET_DELAY_US);
>> + }
>> + }
>
> void __iomem *eth_ldo_rdy;
> u32 val;
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, index + 1);
> if (!res)
> break;
>
> eth_ldo_rdy = devm_ioremap(&pdev->dev, res->start,
> resource_size(res));
> if (!eth_ldo_rdy)
> continue;
>
> val = readl(eth_ldo_rdy) | BIT(0);
> writel(val, eth_ldo_rdy);
> ... whatever sleep is deemed required ...
>
> Other issues:
>
> 1. if devm_ioremap() fails (returns NULL) is it right that we should
> just ignore that resource?
Since each LDO is independent, each LDO is for controlling the
independent Ethernet device, that should be fine to ignore the
failed resource.
>
> 2. Do you need to sleep after each write, or will sleeping after
> writing all of these do? It may be more efficient to detect when
> we have at least one eth_ldo_rdy and then sleep once.
Yes, sleeping can be used after writing all of these, will update the
code as you suggest, thanks Russell.
>
> Thanks.
>
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