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powerpc: pci-ioda: Optimize pnv_ioda_pick_m64_pe()

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bitmap_empty() in pnv_ioda_pick_m64_pe() is O(N) and useless because
the following find_next_bit() does the same work.

Drop it, and while there replace a while() loop with the dedicated
for_each_set_bit().

Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250814190936.381346-3-yury.norov@gmail.com
This commit is contained in:
Yury Norov (NVIDIA)
2025-08-14 15:09:36 -04:00
committed by Madhavan Srinivasan
parent f73338d089
commit bd77a34e9a
1 changed files with 6 additions and 13 deletions
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19
arch/powerpc/platforms/powernv/pci-ioda.c
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@@ -295,7 +295,7 @@ static struct pnv_ioda_pe *pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
unsigned long *pe_alloc __free(bitmap) = NULL;
struct pnv_phb *phb = pci_bus_to_pnvhb(bus);
struct pnv_ioda_pe *master_pe, *pe;
int i;
unsigned int i;
/* Root bus shouldn't use M64 */
if (pci_is_root_bus(bus))
@@ -312,22 +312,15 @@ static struct pnv_ioda_pe *pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
pnv_ioda_reserve_m64_pe(bus, pe_alloc, all);
/*
* the current bus might not own M64 window and that's all
* Figure out the master PE and put all slave PEs to master
* PE's list to form compound PE.
*
* The current bus might not own M64 window and that's all
* contributed by its child buses. For the case, we needn't
* pick M64 dependent PE#.
*/
if (bitmap_empty(pe_alloc, phb->ioda.total_pe_num)) {
return NULL;
}
/*
* Figure out the master PE and put all slave PEs to master
* PE's list to form compound PE.
*/
master_pe = NULL;
i = -1;
while ((i = find_next_bit(pe_alloc, phb->ioda.total_pe_num, i + 1)) <
phb->ioda.total_pe_num) {
for_each_set_bit(i, pe_alloc, phb->ioda.total_pe_num) {
pe = &phb->ioda.pe_array[i];
phb->ioda.m64_segmap[pe->pe_number] = pe->pe_number;