[PATCH 1/2] MTD: pass driver methods through partition wrappers on unpartitioned devices

[Artem Bityutskiy]

On Tue, 2011-12-20 at 10:42 -0800, Mike Dunn wrote:
> Ensure driver methods always go through the wrapper functions in the
> partitioning code by creating a single "partition" on otherwise unpartitioned
> devices.
> 
> Tested with nandsim, onenand_sim, and the diskonchip g4 nand driver (currently
> out-of-tree).
> 
> Signed-off-by: Mike Dunn <mikedunn at newsguy.com>

Looks good to me in general. Does it change anything from the user-space
POW (API/ABI)?

One thing to be aware of: some drivers do like this:

drivers/mtd/maps/plat-ram.c:

        /* check to see if there are any available partitions, or wether
         * to add this device whole */

        err = mtd_device_parse_register(info->mtd, pdata->probes, 0,
                        pdata->partitions, pdata->nr_partitions);
        if (!err)
                dev_info(&pdev->dev, "registered mtd device\n");

        if (pdata->nr_partitions) {
                /* add the whole device. */
                err = mtd_device_register(info->mtd, NULL, 0);
                if (err) {
                        dev_err(&pdev->dev,
                                "failed to register the entire device\n");
                }
        }

Could you please:
1. Try to find drivers like this and kill the redundant mtd_device_register()
   call.
2. There is no guarantee you will find all. So you could add a check in
   mtd_device_parse_register() which would print a warning if the device is
   added for the second time and return. So the code would work and people
   would be able to notice the warning and fix up the driver.

> -		add_mtd_device(&slave->mtd);
> +		ret = add_mtd_device(&slave->mtd);
> +		if (ret == 1)
> +			return -ENODEV;

Is this an unrelated change? Would you separate it out?

-- 
Best Regards,
Artem Bityutskiy
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