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ARM: OMAP: Cleanup OMAP FB SDRAM reservation

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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: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2010-05-22 23:53:45 +01:00
parent 98c672cf1f
commit a1af0fbbba
1 changed files with 44 additions and 17 deletions
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61
arch/arm/plat-omap/fb.c
View file

@ -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;
int i;
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;
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++;
}