[U-Boot] [PATCH v1 07/14] pinctrl: imx: Replace static soc info definitions with run time allocations

[Lukasz Majewski <lukma@denx.de>]

On Wed, 2 Jan 2019 15:14:22 +0100
Marek Vasut <marex@denx.de> wrote:

> On 1/2/19 9:26 AM, Lukasz Majewski wrote:
> > Hi Marek,
> >   
> >> On 1/2/19 12:37 AM, Lukasz Majewski wrote:  
> >>> This commit is necessary to be able to re-use the pinctrl code in
> >>> early SPL to properly configure pins.
> >>>
> >>> The problem is that those "static" structures are placed in the
> >>> SDRAM area, which corresponds to u-boot proper (not even SPL).
> >>> Hence, when one wants to configure pins before relocation via
> >>> DTS/DM, the board hangs (imx6q SoC powered one) as only OCRAM area
> >>> is available (0x009xxxxx).
> >>>
> >>> It is also safe to use calloc in this case, as the early SPL code
> >>> provides it - either full or trimmed version. The allocated memory
> >>> is also correct in respect to the memory area in which the SoC is
> >>> currently running (OCRAM vs. SDRAM).    
> >>
> >> You should be able to access static data in early environment, many
> >> other drivers have no problem with it.   
> > 
> > Have you used pinctrl IMX6Q driver with early DM at SPL?
> >   
> >> I believe there is some more
> >> fundamental problem that needs to be fixed,   
> > 
> > With the current code - which was not used in OCRAM only available
> > memory - the statics are placed in the SDRAM area (0x178x xxxx).
> > 
> > Instead of changing linker script (and validate it for all drivers
> > and boards for SPL and u-boot proper) - the code has been rewritten
> > to use malloc (which is available in the early code - either full
> > blown or simple version).
> >   
> >> hacking around it like
> >> this is just hiding the real issue.  
> > 
> > The real issue is that IMX6Q uses SDRAM memory for statics/globals
> > from the very beginning.  
> Fix it ? What you're implying here is that rodata (preinitialized
> static variables) are misplaced.
> 

The not initialized (as going to be zeroed) 

static struct imx_pinctrl_soc_info imx6_pinctrl_soc_info;
goes to bss section, which is located in SDRAM (not available yet).

 .bss.imx6_pinctrl_soc_info
                0x0000000018200050       0x10 drivers/built-in.o

The other structs in this file, as they have assigned values, are placed
correctly in data (OCRAM area).

I could add __attribute__((section("data"))) in front of this
definition, but this may be a problematic for u-boot proper where this
code is reused (and correctly this data is placed in bss).

Hence, the idea to use calloc explicitly - and with it the correct
(available in the moment) memory is provided.

Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
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