linux-kernel - Re: [PATCH v4 0/5] Support qcom pinctrl protected pins

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Message-ID: <1522053544.23017.109.camel@linux.intel.com>
Date:   Mon, 26 Mar 2018 11:39:04 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Stephen Boyd <swboyd@...omium.org>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Timur Tabi <timur@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Grant Likely <grant.likely@...retlab.ca>,
        linux-gpio@...r.kernel.org
Subject: Re: [PATCH v4 0/5] Support qcom pinctrl protected pins

On Fri, 2018-03-23 at 09:34 -0700, Stephen Boyd wrote:
> This patchset proposes a solution to describing the
> valid                                                                 
>           
> pins for a pin controller in a generic way so that
> qcom                                                                  
>       
> platforms can expose the pins that are really
> available.                                                            
>                 
>                                                                       
>                                                               
> Typically, this has been done by having drivers and
> firmware                                                              
>           
> descriptions only use pins they know they have access to, and
> that                                                                  
> still works now because we no longer read the pin direction
> at                                                                    
>   
> boot. But there are still some userspace drivers and debugfs
> facilities                                                            
>  
> that don't know what pins are available and attempt to read
> everything                                                            
>   
> they can. On qcom platforms, this may lead to a system hang, which
> isn't                                                            
> very nice behavior, even if root is the only user that can trigger
> it.                                                              
>                                                                       
>                                                               
> The proposal is to describe the valid pins and then not allow things
> to                                                             
> cause problems by using the invalid pins. Obviously, the firmware
> may                                                               
> mess this up, so this is mostly a nice to have feature or a safety
> net                                                              
> so that things don't blow up
> easily.                                                               

FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>


> Changes from v3:
>  * Split out allocation of mask into subroutine
>  * Moved that allocation to kmalloc_array()
>  * Updated qcom driver to simplifiy ACPI logic and fix mem leak
> 
> Changes from v2:
>  * Renamed binding to 'gpio-reserved-ranges'
>  * Reworked gpiolib patch to not use irqdomains
>  * Update qcom driver patch to use new valid_mask field
>                                                                       
>                                                               
> Changes from
> v1:                                                                   
>                                                  
>  * Pushed into gpiolib-of core under irq valid line
> logic                                                                 
>           
>  * Fixed up qcom driver patch to free stuff properly and remove custom
> code                                                         
>  * Dropped export patch as it got picked
> up                                                                    
>                      
>  * Renamed binding to 'reserved-gpio-ranges'   
> 
> 
> Stephen Boyd (5):
>   dt-bindings: gpio: Add a gpio-reserved-ranges property
>   gpiolib: Extract mask allocation into subroutine
>   gpiolib: Change bitmap allocation to kmalloc_array
>   gpiolib: Support 'gpio-reserved-ranges' property
>   pinctrl: qcom: Don't allow protected pins to be requested
> 
>  .../devicetree/bindings/gpio/gpio.txt         |  7 +-
>  drivers/gpio/gpiolib-of.c                     | 24 +++++++
>  drivers/gpio/gpiolib.c                        | 66 +++++++++++++++++-
> -
>  drivers/pinctrl/qcom/pinctrl-msm.c            | 65 +++++++++++++++++-
>  include/linux/gpio/driver.h                   | 16 +++++
>  5 files changed, 167 insertions(+), 11 deletions(-)
> 

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy