eeprom/at25: bugfix "not ready" timeout after write

Under certain circumstances msleep(1) within the loop, which waits for the
EEPROM to be finished, might take longer than the timeout.  On the next
loop the status register might now return to be ready and therefore the
loop finishes.  The following check now tests if a timeout occurred and if
so returns an error although the device reported it was ready.

This fix replaces testing the occurrence of the timeout by testing the
"not ready" bit in the status register.
Signed-off-by: NSebastian Heutling <heutling@who-ing.de>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/misc/eeprom/at25.c

@@ -173,6 +173,7 @@ at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
 		unsigned	segment;
 		unsigned	offset = (unsigned) off;
 		u8		*cp = bounce + 1;
+		int		sr;
 
 		*cp = AT25_WREN;
 		status = spi_write(at25->spi, cp, 1);
@@ -214,7 +215,6 @@ at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
 		timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT);
 		retries = 0;
 		do {
-			int	sr;
 
 			sr = spi_w8r8(at25->spi, AT25_RDSR);
 			if (sr < 0 || (sr & AT25_SR_nRDY)) {
@@ -228,7 +228,7 @@ at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
 				break;
 		} while (retries++ < 3 || time_before_eq(jiffies, timeout));
 
-		if (time_after(jiffies, timeout)) {
+		if ((sr < 0) || (sr & AT25_SR_nRDY)) {
 			dev_err(&at25->spi->dev,
 				"write %d bytes offset %d, "
 				"timeout after %u msecs\n",