linux-kernel - Re: [PATCH 1/2] net: allwinner: reset control support

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Message-ID: <f4463df0-6669-fc20-ab8e-c82457e441fb@wirenboard.com>
Date:   Mon, 8 Mar 2021 16:51:14 +0300
From:   Evgeny Boger <boger@...enboard.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Chen-Yu Tsai <wens@...e.org>, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 1/2] net: allwinner: reset control support

Hi, thank you for your review!


3/8/21 4:36 PM, Maxime Ripard пишет:
> Hi,
>
> On Sun, Mar 07, 2021 at 06:13:51AM +0300, Evgeny Boger wrote:
>> R40 (aka V40/A40i/T3) and A10/A20 share the same EMAC IP.
>> However, on R40 the EMAC is gated by default.
>>
>> Signed-off-by: Evgeny Boger <boger@...enboard.com>
> On which device was it tested?
It's custom-made Allwinner A40i device with two IP101GRI PHYs in MII mode.
>> ---
>>   drivers/net/ethernet/allwinner/sun4i-emac.c | 21 ++++++++++++++++++++-
>>   1 file changed, 20 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/allwinner/sun4i-emac.c b/drivers/net/ethernet/allwinner/sun4i-emac.c
>> index 5ed80d9a6b9f..c0ae06dd922c 100644
>> --- a/drivers/net/ethernet/allwinner/sun4i-emac.c
>> +++ b/drivers/net/ethernet/allwinner/sun4i-emac.c
>> @@ -28,6 +28,7 @@
>>   #include <linux/of_platform.h>
>>   #include <linux/platform_device.h>
>>   #include <linux/phy.h>
>> +#include <linux/reset.h>
>>   #include <linux/soc/sunxi/sunxi_sram.h>
>>   
>>   #include "sun4i-emac.h"
>> @@ -85,6 +86,7 @@ struct emac_board_info {
>>   	unsigned int		link;
>>   	unsigned int		speed;
>>   	unsigned int		duplex;
>> +	struct reset_control *reset;
> You should align this with the rest of the other fields

>
>>   
>>   	phy_interface_t		phy_interface;
>>   };
>> @@ -791,6 +793,7 @@ static int emac_probe(struct platform_device *pdev)
>>   	struct net_device *ndev;
>>   	int ret = 0;
>>   	const char *mac_addr;
>> +	struct reset_control *reset;
>>   
>>   	ndev = alloc_etherdev(sizeof(struct emac_board_info));
>>   	if (!ndev) {
>> @@ -852,6 +855,19 @@ static int emac_probe(struct platform_device *pdev)
>>   		goto out_release_sram;
>>   	}
>>   
>> +	reset = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
>> +	if (IS_ERR(reset)) {
>> +		dev_err(&pdev->dev, "unable to request reset\n");
>> +		ret = -ENODEV;
>> +		goto out_release_sram;
>> +	}
> Judging from your commit log, it's not really optional for the R40. The
> way we usually deal with this is to have a structure associated with a
> new compatible and have a flag tell if that compatible requires a reset
> line or not.
>
> The dt binding should also be amended to allow the reset property
>
got it
>> +	db->reset = reset;
>> +	ret = reset_control_deassert(db->reset);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "could not deassert EMAC reset\n");
>> +		goto out_release_sram;
>> +	}
>> +
> The programming guidelines in the datasheet ask that the reset line must
> be deasserted before the clock in enabled.
right, found it at section 3.3.2.6, thanks
>
> Maxime