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Subject: Re: [PATCH v2 2/3] can: m_can: m_can_platform: Add support for
 enabling transceiver
To:     Faiz Abbas <faiz_abbas@ti.com>, Dan Murphy <dmurphy@ti.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, netdev@vger.kernel.org,
        linux-can@vger.kernel.org
Cc:     broonie@kernel.org, lgirdwood@gmail.com, catalin.marinas@arm.com,
        mark.rutland@arm.com, robh+dt@kernel.org, wg@grandegger.com,
        sriram.dash@samsung.com
References: <20200217142836.23702-1-faiz_abbas@ti.com>
 <20200217142836.23702-3-faiz_abbas@ti.com>
 <250f905a-33c3-dd17-15c9-e282299dd742@ti.com>
 <8885c00b-7b73-0448-7e9d-ecb19fe84adf@ti.com>
From:   Marc Kleine-Budde <mkl@pengutronix.de>
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Message-ID: <8a001afe-dc97-fa1e-4e80-20da89eb2105@pengutronix.de>
Date:   Fri, 21 Feb 2020 09:09:18 +0100
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Sender: linux-kernel-owner@vger.kernel.org
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On 2/21/20 8:54 AM, Faiz Abbas wrote:
> 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@ti.com>
>>> Acked-by: Sriram Dash <sriram.dash@samsung.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.

Please don't do this, please handle it properly.

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

If so, then make the runtime pm kconfig option mandatory.

Marc

-- 
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