linux-kernel - Re: [PATCH v2 2/3] can: m_can: m_can_platform: Add support for enabling transceiver

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Message-ID: <8885c00b-7b73-0448-7e9d-ecb19fe84adf@ti.com>
Date:   Fri, 21 Feb 2020 13:24:46 +0530
From:   Faiz Abbas <faiz_abbas@...com>
To:     Dan Murphy <dmurphy@...com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <netdev@...r.kernel.org>, <linux-can@...r.kernel.org>
CC:     <broonie@...nel.org>, <lgirdwood@...il.com>,
        <catalin.marinas@....com>, <mark.rutland@....com>,
        <robh+dt@...nel.org>, <mkl@...gutronix.de>, <wg@...ndegger.com>,
        <sriram.dash@...sung.com>
Subject: Re: [PATCH v2 2/3] can: m_can: m_can_platform: Add support for
 enabling transceiver

Hi Dan,

On 17/02/20 8:40 pm, Dan Murphy wrote:
> Faiz
> 
> On 2/17/20 8:28 AM, Faiz Abbas wrote:
>> CAN transceivers on some boards have a standby line which can be
>> toggled to enable/disable the transceiver. Model this as an optional
>> fixed xceiver regulator.
>>
>> Signed-off-by: Faiz Abbas <faiz_abbas@...com>
>> Acked-by: Sriram Dash <sriram.dash@...sung.com>
>> ---
>>   drivers/net/can/m_can/m_can_platform.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/net/can/m_can/m_can_platform.c
>> b/drivers/net/can/m_can/m_can_platform.c
>> index 38ea5e600fb8..719468fab507 100644
>> --- a/drivers/net/can/m_can/m_can_platform.c
>> +++ b/drivers/net/can/m_can/m_can_platform.c
>> @@ -6,6 +6,7 @@
>>   // Copyright (C) 2018-19 Texas Instruments Incorporated -
>> http://www.ti.com/
>>     #include <linux/platform_device.h>
>> +#include <linux/regulator/consumer.h>
>>     #include "m_can.h"
>>   @@ -57,6 +58,7 @@ static int m_can_plat_probe(struct platform_device
>> *pdev)
>>   {
>>       struct m_can_classdev *mcan_class;
>>       struct m_can_plat_priv *priv;
>> +    struct regulator *reg_xceiver;
>>       struct resource *res;
>>       void __iomem *addr;
>>       void __iomem *mram_addr;
>> @@ -111,6 +113,10 @@ static int m_can_plat_probe(struct
>> platform_device *pdev)
>>         m_can_init_ram(mcan_class);
>>   +    reg_xceiver = devm_regulator_get_optional(&pdev->dev, "xceiver");
>> +    if (PTR_ERR(reg_xceiver) == -EPROBE_DEFER)
>> +        return -EPROBE_DEFER;
>> +
> 
> Where is this regulator enabled?

I have set regulator-boot-on flag in the dt so this didn't require an
enable.

> Shouldn't the regulator be managed by runtime PM as well?
> 

Let me try this out.

Thanks,
Faiz