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Commit a1af0fbb authored by Russell King's avatar Russell King
Browse files

ARM: OMAP: Cleanup OMAP FB SDRAM reservation 



The logic in this file is rather convoluted, but essentially:

1. region type 0 is SDRAM
2. referring to the code fragment
                if (set_fbmem_region_type(&rg, OMAPFB_MEMTYPE_SDRAM,
                                          sdram_start, sdram_size) < 0 ||
                    (rg.type != OMAPFB_MEMTYPE_SDRAM))
                        continue;
   - if rg.type is not OMAPFB_MEMTYPE_SDRAM, set_fbmem_region_type()
     returns zero immediately (since rg.type is non-zero), and so we
     'continue'.
   - if rg.type is OMAPFB_MEMTYPE_SDRAM, and rg.paddr is zero,
     we fall through.
   - if rg.type is OMAPFB_MEMTYPE_SDRAM, and the region lies within
     SDRAM, we fall through.
   - if rg.type is OMAPFB_MEMTYPE_SDRAM, and the region is not within
     SDRAM, we 'continue'.
3. check_fbmem_region seems unnecessary.
   - we know rg.type is OMAPFB_MEMTYPE_SDRAM
   - we can check rg.size independently
   - bootmem_reserve() can check for overlapping reservations itself
   - we've already validated that the requested region lies within SDRAM.
4. avoid BUG()ing if the region entry is already set; print an error,
   and mark the configuration invalid - at least we'll continue booting
   so the error message has a chance of being logged/visible via serial
   console.

With these changes in place, it makes the code much easier to understand
and hence easier to convert to LMB.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 98c672cf

arch/arm/plat-omap/fb.c

+44 −17
Original line number Diff line number Diff line
@@ -171,49 +171,76 @@ static int check_fbmem_region(int region_idx, struct omapfb_mem_region *rg, 
	return 0;

}



static int valid_sdram(unsigned long addr, unsigned long size)

{

	struct bootmem_data *bdata = NODE_DATA(0)->bdata;

	unsigned long sdram_start, sdram_end;



	sdram_start = bdata->node_min_pfn << PAGE_SHIFT;

	sdram_end = bdata->node_low_pfn << PAGE_SHIFT;



	return addr >= sdram_start && sdram_end - addr >= size;

}



static int reserve_sdram(unsigned long addr, unsigned long size)

{

	return reserve_bootmem(addr, size, BOOTMEM_EXCLUSIVE);

}



/*

 * Called from map_io. We need to call to this early enough so that we

 * can reserve the fixed SDRAM regions before VM could get hold of them.

 */

void __init omapfb_reserve_sdram(void)

{

	struct bootmem_data	*bdata;

	unsigned long		sdram_start, sdram_size;

	unsigned long		reserved;

	unsigned long reserved = 0;

	int i;



	if (config_invalid)

		return;



	bdata = NODE_DATA(0)->bdata;

	sdram_start = bdata->node_min_pfn << PAGE_SHIFT;

	sdram_size = (bdata->node_low_pfn << PAGE_SHIFT) - sdram_start;

	reserved = 0;

	for (i = 0; ; i++) {

		struct omapfb_mem_region rg;



		if (get_fbmem_region(i, &rg) < 0)

			break;



		if (i == OMAPFB_PLANE_NUM) {

			printk(KERN_ERR

				"Extraneous FB mem configuration entries\n");

			pr_err("Extraneous FB mem configuration entries\n");

			config_invalid = 1;

			return;

		}



		/* Check if it's our memory type. */

		if (set_fbmem_region_type(&rg, OMAPFB_MEMTYPE_SDRAM,

				          sdram_start, sdram_size) < 0 ||

		    (rg.type != OMAPFB_MEMTYPE_SDRAM))

		if (rg.type != OMAPFB_MEMTYPE_SDRAM)

			continue;

		BUG_ON(omapfb_config.mem_desc.region[i].size);

		if (check_fbmem_region(i, &rg, sdram_start, sdram_size) < 0) {



		/* Check if the region falls within SDRAM */

		if (rg.paddr && !valid_sdram(rg.paddr, rg.size))

			continue;



		if (rg.size == 0) {

			pr_err("Zero size for FB region %d\n", i);

			config_invalid = 1;

			return;

		}



		if (rg.paddr) {

			reserve_bootmem(rg.paddr, rg.size, BOOTMEM_DEFAULT);

			if (reserve_sdram(rg.paddr, rg.size)) {

				pr_err("Trying to use reserved memory for FB region %d\n",

					i);

				config_invalid = 1;

				return;

			}

			reserved += rg.size;

		}



		if (omapfb_config.mem_desc.region[i].size) {

			pr_err("FB region %d already set\n", i);

			config_invalid = 1;

			return;

		}



		omapfb_config.mem_desc.region[i] = rg;

		configured_regions++;

	}