linux-kernel - Re: [PATCH v3 2/2] mtd: spi-nor: Add support for flash reset

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Message-ID: <53b7f736-1f5f-7b89-671b-536bb4e02d77@microchip.com>
Date:   Wed, 5 Oct 2022 05:48:45 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <sai.krishna.potthuri@....com>, <pratyush@...nel.org>,
        <michael@...le.cc>, <miquel.raynal@...tlin.com>, <richard@....at>,
        <vigneshr@...com>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>
CC:     <devicetree@...r.kernel.org>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <saikrishna12468@...il.com>,
        <git@....com>
Subject: Re: [PATCH v3 2/2] mtd: spi-nor: Add support for flash reset

On 10/3/22 13:06, Potthuri, Sai Krishna wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Hi Tudor Ambarus,
> 
>> -----Original Message-----
>> From: Tudor.Ambarus@...rochip.com <Tudor.Ambarus@...rochip.com>
>> Sent: Monday, October 3, 2022 3:13 PM
>> To: Potthuri, Sai Krishna <sai.krishna.potthuri@....com>;
>> pratyush@...nel.org; michael@...le.cc; miquel.raynal@...tlin.com;
>> richard@....at; vigneshr@...com; robh+dt@...nel.org;
>> krzysztof.kozlowski+dt@...aro.org
>> Cc: devicetree@...r.kernel.org; linux-mtd@...ts.infradead.org; linux-
>> kernel@...r.kernel.org; saikrishna12468@...il.com; git (AMD-Xilinx)
>> <git@....com>
>> Subject: Re: [PATCH v3 2/2] mtd: spi-nor: Add support for flash reset
>>
>> On 9/8/22 09:44, Sai Krishna Potthuri wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know
>>> the content is safe
>>>
>>> Add support for spi-nor flash reset via GPIO controller by reading the
>>> reset-gpio property. If there is a valid GPIO specifier then reset
>>> will be performed by asserting and deasserting the GPIO using gpiod
>>> APIs otherwise it will not perform any operation.
>>>
>>> Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@....com>
>>> Reviewed-by: Michael Walle <michael@...le.cc>
>>> ---
>>>  drivers/mtd/spi-nor/core.c | 25 +++++++++++++++++++++++++
>>>  1 file changed, 25 insertions(+)
>>>
>>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
>>> index f2c64006f8d7..a78ab9bae2be 100644
>>> --- a/drivers/mtd/spi-nor/core.c
>>> +++ b/drivers/mtd/spi-nor/core.c
>>> @@ -2933,6 +2933,27 @@ static void spi_nor_set_mtd_info(struct spi_nor
>> *nor)
>>>         mtd->_put_device = spi_nor_put_device;  }
>>>
>>> +static int spi_nor_hw_reset(struct spi_nor *nor) {
>>> +       struct gpio_desc *reset;
>>> +
>>> +       reset = devm_gpiod_get_optional(nor->dev, "reset",
>> GPIOD_OUT_LOW);
>>> +       if (IS_ERR_OR_NULL(reset))
>>> +               return PTR_ERR_OR_ZERO(reset);
>>> +
>>> +       /*
>>> +        * Experimental delay values by looking at different flash device
>>> +        * vendors datasheets.
>>> +        */
>>> +       usleep_range(1, 5);
>>> +       gpiod_set_value_cansleep(reset, 1);
>>> +       usleep_range(100, 150);
>>> +       gpiod_set_value_cansleep(reset, 0);
>>> +       usleep_range(1000, 1200);
>>> +
>>> +       return 0;
>>> +}
>>> +
>>>  int spi_nor_scan(struct spi_nor *nor, const char *name,
>>>                  const struct spi_nor_hwcaps *hwcaps)  { @@ -2965,6
>>> +2986,10 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
>>>         if (!nor->bouncebuf)
>>>                 return -ENOMEM;
>>>
>>> +       ret = spi_nor_hw_reset(nor);
>>
>> Should we condition the calling of this method by the absence of the
>> "broken-flash-reset"
>> dt prop?
> This is the suggestion from Michael on top of my initial series for which
> i also agreed to have this call unconditionally. If device tree is having this
> reset property then we can do the reset in any case.
> 

Okay.

-- 
Cheers,
ta