[U-Boot] [PATCH v6 2/2] common: Generic firmware loader for file system

[Chee, Tien Fong]

On Thu, 2018-01-18 at 06:57 +0100, Simon Goldschmidt wrote:
> On 27.12.2017 06:04, tien.fong.chee at intel.com wrote:
> > 
> > From: Tien Fong Chee <tien.fong.chee at intel.com>
> > 
> > This is file system generic loader which can be used to load
> > the file image from the storage into target such as memory.
> > The consumer driver would then use this loader to program whatever,
> > ie. the FPGA device.
> > 
> > Signed-off-by: Tien Fong Chee <tien.fong.chee at intel.com>
> > ---
> >   common/Makefile            |   1 +
> >   common/fs_loader.c         | 309
> > +++++++++++++++++++++++++++++++++++++++++++++
> >   doc/README.firmware_loader |  76 +++++++++++
> >   include/fs_loader.h        |  28 ++++
> >   4 files changed, 414 insertions(+)
> >   create mode 100644 common/fs_loader.c
> >   create mode 100644 doc/README.firmware_loader
> >   create mode 100644 include/fs_loader.h
> <snip>
> 
> > 
> > +#if defined(CONFIG_SPL_MMC_SUPPORT) && defined(CONFIG_SPL_BUILD)
> > +static int init_mmc(void)
> > +{
> > +	/* Just for the case MMC is not yet initialized */
> > +	struct mmc *mmc = NULL;
> > +	int err;
> > +
> > +	spl_mmc_find_device(&mmc, spl_boot_device());
> > +
> > +	err = mmc_init(mmc);
> > +	if (err) {
> > +		printf("spl: mmc init failed with error: %d\n",
> > err);
> > +		return err;
> > +	}
> > +
> > +	return err;
> > +}
> I see two problems here: First, you're ignoring the return value of 
> spl_mmc_find_device() and initialize 'mmc' to NULL instead. Wouldn't
> it 
> be better to let 'mmc' be uninitialized and return the error code 
> returned by spl_mmc_find_device() if there is one?
> 
Yeah, you are right, i should add the check on the return value. I
think that would better to initialize NULL to mmc, because there is no
checking on the mmc in spl_mmc_find_device(), so that is possible
memory access violation/abort can be happended if unknown value in mmc
pointer.

> Second, using spl_boot_device() would prevent making the loader work
> on 
> mach-socfpga when spl is not loaded from mmc, right?
> 
> E.g. for the case I'm currently trying to fix (boot from qspi), this 
> loader would not work although there's technically no reason since
> the 
> platform only has one mmc. The call to spl_boot_device() could be 
> replaced by the exact value here for platforms that only have one
> mmc. I 
> don't know how to fix that, though.
> 
The main purpose here is to initialize the mmc driver. So which storage
user wants to load the file is totally depend what storage such as mmc
user defines in location->name. Loader would init the storage based on
the storage defined in location->name before accessing it. Since the
loader only support file system at this moment, i would suggest FAT fs 
for mmc and ubi fs for qspi.

> Regards,
> Simon
>