linux-kernel - Re: [PATCH] mmc: omap_hsmmc: Update driver to support without regulators

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Message-ID: <55AEA008.6050808@ti.com>
Date:	Tue, 21 Jul 2015 14:39:52 -0500
From:	"Franklin S Cooper Jr." <fcooper@...com>
To:	Ulf Hansson <ulf.hansson@...aro.org>
CC:	linux-omap <linux-omap@...r.kernel.org>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	<kishon@...com>, <rogerq@...com>,
	Lokesh Vutla <lokeshvutla@...com>,
	Murali Karicheri <m-karicheri2@...com>
Subject: Re: [PATCH] mmc: omap_hsmmc: Update driver to support without regulators



On 07/21/2015 06:40 AM, Ulf Hansson wrote:
> On 14 July 2015 at 21:29, Franklin S Cooper Jr <fcooper@...com> wrote:
>> From: Roger Quadros <rogerq@...com>
>>
>> Update driver to support without regulators.
>>
>> Without this patch boards that do not enable regulator config options will
>> fail to boot with a kernel panic.
> I guess that's because the rootfs is mounted on the card that doesn't
> get detected, right?
No at ramfs was used to validate this and was loaded via ethernet in U-boot.
>
>> 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>
>> ---
>>  Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt |  2 ++
>>  drivers/mmc/host/omap_hsmmc.c                           | 14 ++++++++++----
>>  2 files changed, 12 insertions(+), 4 deletions(-)
>>
>> 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 b2b411d..16c870f 100644
>> --- a/drivers/mmc/host/omap_hsmmc.c
>> +++ b/drivers/mmc/host/omap_hsmmc.c
>> @@ -1551,10 +1551,13 @@ static void omap_hsmmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>>         if (ios->power_mode != host->power_mode) {
>>                 switch (ios->power_mode) {
>>                 case MMC_POWER_OFF:
>> -                       mmc_pdata(host)->set_power(host->dev, 0, 0);
>> +                       if (host->use_reg)
>> +                               mmc_pdata(host)->set_power(host->dev, 0, 0);
>>                         break;
>>                 case MMC_POWER_UP:
>> -                       mmc_pdata(host)->set_power(host->dev, 1, ios->vdd);
>> +                       if (host->use_reg)
>> +                               mmc_pdata(host)->set_power(host->dev, 1,
>> +                                                          ios->vdd);
>>                         break;
>>                 case MMC_POWER_ON:
>>                         do_send_init_stream = 1;
>> @@ -2082,10 +2085,13 @@ static int omap_hsmmc_probe(struct platform_device *pdev)
>>                 if (ret)
>>                         goto err_irq;
>>                 host->use_reg = 1;
>> +               mmc->ocr_avail = mmc_pdata(host)->ocr_mask;
>> +       } else {
>> +               ret = mmc_of_parse_voltage(pdev->dev.of_node, &mmc->ocr_avail);
>> +               if (ret)
>> +                       goto err_irq;
>>         }
>>
>> -       mmc->ocr_avail = mmc_pdata(host)->ocr_mask;
>> -
>>         omap_hsmmc_disable_irq(host);
>>
>>         /*
>> --
>> 1.9.1
>>
>> --
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> No, I don't like this patch. If your board have regulators which can
> be used to find out the voltage levels, we shall use them. We shall
> not use DT to workaround this.
>
> So, perhaps the Kconfig section for omap_hsmmc should select
> CONFIG_REGULATOR (and friends)?
Looking at the code the "ifdefCONFIG_REGULATOR" and the usage of use_reg
(use regulator) shows that this driver is suppose to support boards that
don't have the regulator framework enabled.

This patches insures that this driver can work without the regulator framework
which is currently broken.

>
> Kind regards
> Uffe

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