altera_qspi: skip erase if the sector is blank

Skip erase if the sector is blank. The sector erase is slow, and
may take 0.7 sec typically or up to 3 sec worst-case.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>

diff --git a/drivers/mtd/altera_qspi.c b/drivers/mtd/altera_qspi.c
index b0d4f2c..8a630a6 100644 (file)
--- a/drivers/mtd/altera_qspi.c
+++ b/drivers/mtd/altera_qspi.c
@@ -131,24 +131,35 @@ static int altera_qspi_erase(struct mtd_info *mtd, struct erase_info *instr)
        size_t end = addr + len;
        u32 sect;
        u32 stat;
+       u32 *flash, *last;
 
        instr->state = MTD_ERASING;
        addr &= ~(mtd->erasesize - 1); /* get lower aligned address */
        while (addr < end) {
-               sect = addr / mtd->erasesize;
-               sect <<= 8;
-               sect |= QUADSPI_MEM_OP_SECTOR_ERASE;
-               debug("erase %08x\n", sect);
-               writel(sect, &regs->mem_op);
-               stat = readl(&regs->isr);
-               if (stat & QUADSPI_ISR_ILLEGAL_ERASE) {
-                       /* erase failed, sector might be protected */
-                       debug("erase %08x fail %x\n", sect, stat);
-                       writel(stat, &regs->isr); /* clear isr */
-                       instr->fail_addr = addr;
-                       instr->state = MTD_ERASE_FAILED;
-                       mtd_erase_callback(instr);
-                       return -EIO;
+               flash = pdata->base + addr;
+               last = pdata->base + addr + mtd->erasesize;
+               /* skip erase if sector is blank */
+               while (flash < last) {
+                       if (readl(flash) != 0xffffffff)
+                               break;
+                       flash++;
+               }
+               if (flash < last) {
+                       sect = addr / mtd->erasesize;
+                       sect <<= 8;
+                       sect |= QUADSPI_MEM_OP_SECTOR_ERASE;
+                       debug("erase %08x\n", sect);
+                       writel(sect, &regs->mem_op);
+                       stat = readl(&regs->isr);
+                       if (stat & QUADSPI_ISR_ILLEGAL_ERASE) {
+                               /* erase failed, sector might be protected */
+                               debug("erase %08x fail %x\n", sect, stat);
+                               writel(stat, &regs->isr); /* clear isr */
+                               instr->fail_addr = addr;
+                               instr->state = MTD_ERASE_FAILED;
+                               mtd_erase_callback(instr);
+                               return -EIO;
+                       }
                }
                addr += mtd->erasesize;
        }