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[PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

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  [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS Kishon Vijay Abraham I <kishon@ti.com> - 2016-01-14 10:20 +0100
    Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable  CONFIG_REGULATOR_PBIAS Sebastian Reichel <sre@kernel.org> - 2016-01-14 13:10 +0100
      Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable  CONFIG_REGULATOR_PBIAS Kishon Vijay Abraham I <kishon@ti.com> - 2016-01-14 13:50 +0100
        Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable  CONFIG_REGULATOR_PBIAS Tony Lindgren <tony@atomide.com> - 2016-01-14 18:00 +0100
      Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable  CONFIG_REGULATOR_PBIAS Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-01-14 18:30 +0100
        Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable  CONFIG_REGULATOR_PBIAS Sebastian Reichel <sre@kernel.org> - 2016-01-14 23:50 +0100
          Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable  CONFIG_REGULATOR_PBIAS Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-01-15 10:20 +0100

#1309108 — [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

Since v4.3+, CONFIG_REGULATOR_PBIAS should be enabled (for platforms that
have PBIAS regulator) in order for MMC1 to work.

Add a more verbose print to help enable CONFIG_REGULATOR_PBIAS for users
using a olddefconfig or a custom .config.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
---
 drivers/mmc/host/omap_hsmmc.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index 7fb0753..7086bd6 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -503,8 +503,11 @@ static int omap_hsmmc_reg_get(struct omap_hsmmc_host *host)
 	host->pbias = devm_regulator_get_optional(host->dev, "pbias");
 	if (IS_ERR(host->pbias)) {
 		ret = PTR_ERR(host->pbias);
-		if ((ret != -ENODEV) && host->dev->of_node)
+		if ((ret != -ENODEV) && host->dev->of_node) {
+			dev_err(host->dev,
+			"SD card detect fail? enable CONFIG_REGULATOR_PBIAS\n");
 			return ret;
+		}
 		dev_dbg(host->dev, "unable to get pbias regulator %ld\n",
 			PTR_ERR(host->pbias));
 		host->pbias = NULL;
-- 
1.7.9.5

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#1309208 — Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

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Hi,

On Thu, Jan 14, 2016 at 02:45:20PM +0530, Kishon Vijay Abraham I wrote:
> Since v4.3+, CONFIG_REGULATOR_PBIAS should be enabled (for platforms that
> have PBIAS regulator) in order for MMC1 to work.
> 
> Add a more verbose print to help enable CONFIG_REGULATOR_PBIAS for users
> using a olddefconfig or a custom .config.
> 
> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> ---
>  drivers/mmc/host/omap_hsmmc.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> index 7fb0753..7086bd6 100644
> --- a/drivers/mmc/host/omap_hsmmc.c
> +++ b/drivers/mmc/host/omap_hsmmc.c
> @@ -503,8 +503,11 @@ static int omap_hsmmc_reg_get(struct omap_hsmmc_host *host)
>  	host->pbias = devm_regulator_get_optional(host->dev, "pbias");
>  	if (IS_ERR(host->pbias)) {
>  		ret = PTR_ERR(host->pbias);
> -		if ((ret != -ENODEV) && host->dev->of_node)
> +		if ((ret != -ENODEV) && host->dev->of_node) {
> +			dev_err(host->dev,
> +			"SD card detect fail? enable CONFIG_REGULATOR_PBIAS\n");
>  			return ret;
> +		}
>  		dev_dbg(host->dev, "unable to get pbias regulator %ld\n",
>  			PTR_ERR(host->pbias));
>  		host->pbias = NULL;


Is there a good reason against adding "depends on REGULATOR_PBIAS"
to MMC_OMAP_HS? I guess it's required for most systems and the regulator
driver is just 250 loc. I am aware, that this will disable the
hsmmc driver for 'make oldconfig', but I guess that will be noticed
in a similar way your warning is noticed.

The advantage of having the depends line is, that people configuring
their kernel have a chance to notice the regulator requirement
during configuration.

Anyways, this message improves the situation, so:

Acked-By: Sebastian Reichel <sre@kernel.org>

-- Sebastian

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#1309248 — Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

Hi,

On Thursday 14 January 2016 05:37 PM, Sebastian Reichel wrote:
> Hi,
> 
> On Thu, Jan 14, 2016 at 02:45:20PM +0530, Kishon Vijay Abraham I wrote:
>> Since v4.3+, CONFIG_REGULATOR_PBIAS should be enabled (for platforms that
>> have PBIAS regulator) in order for MMC1 to work.
>>
>> Add a more verbose print to help enable CONFIG_REGULATOR_PBIAS for users
>> using a olddefconfig or a custom .config.
>>
>> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
>> ---
>>  drivers/mmc/host/omap_hsmmc.c |    5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
>> index 7fb0753..7086bd6 100644
>> --- a/drivers/mmc/host/omap_hsmmc.c
>> +++ b/drivers/mmc/host/omap_hsmmc.c
>> @@ -503,8 +503,11 @@ static int omap_hsmmc_reg_get(struct omap_hsmmc_host *host)
>>  	host->pbias = devm_regulator_get_optional(host->dev, "pbias");
>>  	if (IS_ERR(host->pbias)) {
>>  		ret = PTR_ERR(host->pbias);
>> -		if ((ret != -ENODEV) && host->dev->of_node)
>> +		if ((ret != -ENODEV) && host->dev->of_node) {
>> +			dev_err(host->dev,
>> +			"SD card detect fail? enable CONFIG_REGULATOR_PBIAS\n");
>>  			return ret;
>> +		}
>>  		dev_dbg(host->dev, "unable to get pbias regulator %ld\n",
>>  			PTR_ERR(host->pbias));
>>  		host->pbias = NULL;
> 
> 
> Is there a good reason against adding "depends on REGULATOR_PBIAS"
> to MMC_OMAP_HS? I guess it's required for most systems and the regulator
> driver is just 250 loc. I am aware, that this will disable the
> hsmmc driver for 'make oldconfig', but I guess that will be noticed
> in a similar way your warning is noticed.

hmm.. only MMC1 requires PBIAS so I'm not sure if it's okay to add depends on
REGULATOR_PBIAS for the HSMMC driver as such. And as you said it'll also
disable the hsmmc driver if oldconfig is used. But do we get a warning?

Thanks
Kishon

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#1309485 — Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

* Kishon Vijay Abraham I <kishon@ti.com> [160114 04:39]:
> On Thursday 14 January 2016 05:37 PM, Sebastian Reichel wrote:
> > 
> > Is there a good reason against adding "depends on REGULATOR_PBIAS"
> > to MMC_OMAP_HS? I guess it's required for most systems and the regulator
> > driver is just 250 loc. I am aware, that this will disable the
> > hsmmc driver for 'make oldconfig', but I guess that will be noticed
> > in a similar way your warning is noticed.
> 
> hmm.. only MMC1 requires PBIAS so I'm not sure if it's okay to add depends on
> REGULATOR_PBIAS for the HSMMC driver as such. And as you said it'll also
> disable the hsmmc driver if oldconfig is used. But do we get a warning?

Adding depends there is a bit wrong, many designs are not using MMC1
but use eMMC on the other controllers instead. I think the runtime
warning is best we can do here to keep things modular.

Regards,

Tony

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#1309503 — Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

On Thu, Jan 14, 2016 at 01:07:06PM +0100, Sebastian Reichel wrote:
> Hi,
> 
> On Thu, Jan 14, 2016 at 02:45:20PM +0530, Kishon Vijay Abraham I wrote:
> > Since v4.3+, CONFIG_REGULATOR_PBIAS should be enabled (for platforms that
> > have PBIAS regulator) in order for MMC1 to work.
> > 
> > Add a more verbose print to help enable CONFIG_REGULATOR_PBIAS for users
> > using a olddefconfig or a custom .config.
> > 
> > Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> > ---
> >  drivers/mmc/host/omap_hsmmc.c |    5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> > index 7fb0753..7086bd6 100644
> > --- a/drivers/mmc/host/omap_hsmmc.c
> > +++ b/drivers/mmc/host/omap_hsmmc.c
> > @@ -503,8 +503,11 @@ static int omap_hsmmc_reg_get(struct omap_hsmmc_host *host)
> >  	host->pbias = devm_regulator_get_optional(host->dev, "pbias");
> >  	if (IS_ERR(host->pbias)) {
> >  		ret = PTR_ERR(host->pbias);
> > -		if ((ret != -ENODEV) && host->dev->of_node)
> > +		if ((ret != -ENODEV) && host->dev->of_node) {
> > +			dev_err(host->dev,
> > +			"SD card detect fail? enable CONFIG_REGULATOR_PBIAS\n");
> >  			return ret;
> > +		}
> >  		dev_dbg(host->dev, "unable to get pbias regulator %ld\n",
> >  			PTR_ERR(host->pbias));
> >  		host->pbias = NULL;
> 
> 
> Is there a good reason against adding "depends on REGULATOR_PBIAS"
> to MMC_OMAP_HS?

There are very good reasons not to do this: that will result in
configurations where MMC_OMAP_HS was set but without REGULATOR_PBIAS
ending up with MMC_OMAP_HS being disabled.  That doesn't help the
root problem, which is "why has the kernel boot regressed for my
previous working configuration?"

The solution proposed here adds a message to the boot which points
out fair and square what needs to be done to rectify the boot
failure.  Adding a dependency just brings up the question "where
has my MMC driver gone?"

-- 
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

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#1309733 — Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

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Hi,

On Thu, Jan 14, 2016 at 05:25:49PM +0000, Russell King - ARM Linux wrote:
> On Thu, Jan 14, 2016 at 01:07:06PM +0100, Sebastian Reichel wrote:
> > On Thu, Jan 14, 2016 at 02:45:20PM +0530, Kishon Vijay Abraham I wrote:
> > > Since v4.3+, CONFIG_REGULATOR_PBIAS should be enabled (for platforms that
> > > have PBIAS regulator) in order for MMC1 to work.
> > > 
> > > Add a more verbose print to help enable CONFIG_REGULATOR_PBIAS for users
> > > using a olddefconfig or a custom .config.
> > > 
> > > Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> > > ---
> > >  drivers/mmc/host/omap_hsmmc.c |    5 ++++-
> > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> > > index 7fb0753..7086bd6 100644
> > > --- a/drivers/mmc/host/omap_hsmmc.c
> > > +++ b/drivers/mmc/host/omap_hsmmc.c
> > > @@ -503,8 +503,11 @@ static int omap_hsmmc_reg_get(struct omap_hsmmc_host *host)
> > >  	host->pbias = devm_regulator_get_optional(host->dev, "pbias");
> > >  	if (IS_ERR(host->pbias)) {
> > >  		ret = PTR_ERR(host->pbias);
> > > -		if ((ret != -ENODEV) && host->dev->of_node)
> > > +		if ((ret != -ENODEV) && host->dev->of_node) {
> > > +			dev_err(host->dev,
> > > +			"SD card detect fail? enable CONFIG_REGULATOR_PBIAS\n");
> > >  			return ret;
> > > +		}
> > >  		dev_dbg(host->dev, "unable to get pbias regulator %ld\n",
> > >  			PTR_ERR(host->pbias));
> > >  		host->pbias = NULL;
> > 
> > 
> > Is there a good reason against adding "depends on REGULATOR_PBIAS"
> > to MMC_OMAP_HS?
> 
> There are very good reasons not to do this: that will result in
> configurations where MMC_OMAP_HS was set but without REGULATOR_PBIAS
> ending up with MMC_OMAP_HS being disabled.  That doesn't help the
> root problem, which is "why has the kernel boot regressed for my
> previous working configuration?"
> 
> The solution proposed here adds a message to the boot which points
> out fair and square what needs to be done to rectify the boot
> failure.  Adding a dependency just brings up the question "where
> has my MMC driver gone?"

The best thing would be to have no regression. Just printing a
message means I have to build another kernel. But more importantly
the message may not be visible by the user - e.g. if the display has
not yet been initialized.

-- Sebastian

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#1309980 — Re: [PATCH] mmc: host: omap_hsmmc: add a verbose print to enable CONFIG_REGULATOR_PBIAS

On Thu, Jan 14, 2016 at 11:40:25PM +0100, Sebastian Reichel wrote:
> On Thu, Jan 14, 2016 at 05:25:49PM +0000, Russell King - ARM Linux wrote:
> > There are very good reasons not to do this: that will result in
> > configurations where MMC_OMAP_HS was set but without REGULATOR_PBIAS
> > ending up with MMC_OMAP_HS being disabled.  That doesn't help the
> > root problem, which is "why has the kernel boot regressed for my
> > previous working configuration?"
> > 
> > The solution proposed here adds a message to the boot which points
> > out fair and square what needs to be done to rectify the boot
> > failure.  Adding a dependency just brings up the question "where
> > has my MMC driver gone?"
> 
> The best thing would be to have no regression. Just printing a
> message means I have to build another kernel. But more importantly
> the message may not be visible by the user - e.g. if the display has
> not yet been initialized.

I agree in principle, but that's not possible here (see Tony's mails
on why the PBIAS stuff needs to be optional.)  I'd agree with changing
the Kconfig if PBIAS were a hard and fast requirement, but it isn't.

-- 
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

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