linux-kernel - Re: [PATCH v2 16/16] mmc: host: omap_hsmmc: use "mmc_of_parse_voltage" to get ocr

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Message-ID: <564317B9.8010502@ti.com>
Date:	Wed, 11 Nov 2015 12:26:01 +0200
From:	Roger Quadros <rogerq@...com>
To:	Ulf Hansson <ulf.hansson@...aro.org>,
	Kishon Vijay Abraham I <kishon@...com>
CC:	Andreas Fenkart <afenkart@...il.com>,
	Tony Lindgren <tony@...mide.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	linux-omap <linux-omap@...r.kernel.org>,
	Sekhar Nori <nsekhar@...com>,
	Lokesh Vutla <lokeshvutla@...com>,
	Murali Karicheri <m-karicheri2@...com>,
	Franklin S Cooper Jr <fcooper@...com>
Subject: Re: [PATCH v2 16/16] mmc: host: omap_hsmmc: use
 "mmc_of_parse_voltage" to get ocr_avail

Hi,

On 25/08/15 17:50, Ulf Hansson wrote:
> On 3 August 2015 at 14:26, Kishon Vijay Abraham I <kishon@...com> wrote:
>> From: Roger Quadros <rogerq@...com>
>>
>> For platforms that doesn't have explicit regulator control in MMC,
>> populate voltage-ranges in MMC device tree node and use
>> mmc_of_parse_voltage to get ocr_avail
> 
> I don't like this.
> 
> If we are able to fetch the OCR mask via an external regulator, that
> shall be done.

Agreed.
> 
> I think the mmc_of_parse_voltage() API and the corresponding DT
> binding it parses, should be used for those HW when we don't have an
> external regulator to use. For example if the MMC controller itself
> somehow controls the voltage levels. Is that really the case for you?

What shall be done if there is no software control of the external regulator
and it is fixed at a certain voltage?

cheers,
-roger

> 
> Kind regards
> Uffe
> 
>>
>> Signed-off-by: Roger Quadros <rogerq@...com>
>> Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
>> Signed-off-by: Murali Karicheri <m-karicheri2@...com>
>> Signed-off-by: Franklin S Cooper Jr <fcooper@...com>
>> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
>> ---
>>  .../devicetree/bindings/mmc/ti-omap-hsmmc.txt      |    2 ++
>>  drivers/mmc/host/omap_hsmmc.c                      |    9 ++++++++-
>>  2 files changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
>> index 76bf087..2408e87 100644
>> --- a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
>> +++ b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
>> @@ -22,6 +22,8 @@ ti,dual-volt: boolean, supports dual voltage cards
>>  ti,non-removable: non-removable slot (like eMMC)
>>  ti,needs-special-reset: Requires a special softreset sequence
>>  ti,needs-special-hs-handling: HSMMC IP needs special setting for handling High Speed
>> +voltage-ranges: Specify the voltage range supported if regulator framework
>> +isn't enabled.
>>  dmas: List of DMA specifiers with the controller specific format
>>  as described in the generic DMA client binding. A tx and rx
>>  specifier is required.
>> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
>> index 15973f1..d884d8f 100644
>> --- a/drivers/mmc/host/omap_hsmmc.c
>> +++ b/drivers/mmc/host/omap_hsmmc.c
>> @@ -2184,7 +2184,13 @@ static int omap_hsmmc_probe(struct platform_device *pdev)
>>                         goto err_irq;
>>         }
>>
>> -       mmc->ocr_avail = mmc_pdata(host)->ocr_mask;
>> +       if (!mmc_pdata(host)->ocr_mask) {
>> +               ret = mmc_of_parse_voltage(pdev->dev.of_node, &mmc->ocr_avail);
>> +               if (ret)
>> +                       goto err_parse_voltage;
>> +       } else {
>> +               mmc->ocr_avail = mmc_pdata(host)->ocr_mask;
>> +       }
>>
>>         omap_hsmmc_disable_irq(host);
>>
>> @@ -2224,6 +2230,7 @@ static int omap_hsmmc_probe(struct platform_device *pdev)
>>
>>  err_slot_name:
>>         mmc_remove_host(mmc);
>> +err_parse_voltage:
>>         omap_hsmmc_reg_put(host);
>>  err_irq:
>>         device_init_wakeup(&pdev->dev, false);
>> --
>> 1.7.9.5
>>
--
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