[PATCH] dz.c: Always check if it is safe to console_putchar()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



 Polled transmission is tricky enough with the DZ11 design.  While "loop" 
is set to a high value, conceptually you are not allowed to transmit 
without checking whether the device offers the right transmission line 
(yes, it is the device that selects the line -- the driver has no control 
over it other than disabling the transmitter offered if it is the wrong 
one), so the loop has to be run at least once.

 Well, the '1977 or PDP11 view of how serial lines should be handled...  
Except that the serial interface used to be quite an impressive board back 
then rather than chip.

Signed-off-by: Maciej W. Rozycki <[email protected]>
---
 Tested with checkpatch.pl and at the run-time -- MIPS/Linux on a 
DECstation 5000/200.

 Please apply,

  Maciej

patch-mips-2.6.18-20060920-dz-putchar-0
diff -up --recursive --new-file linux-mips-2.6.18-20060920.macro/drivers/serial/dz.c linux-mips-2.6.18-20060920/drivers/serial/dz.c
--- linux-mips-2.6.18-20060920.macro/drivers/serial/dz.c	2006-11-23 05:17:01.000000000 +0000
+++ linux-mips-2.6.18-20060920/drivers/serial/dz.c	2007-01-14 00:07:02.000000000 +0000
@@ -686,7 +686,7 @@ static void dz_console_putchar(struct ua
 	iob();
 	spin_unlock_irqrestore(&dport->port.lock, flags);
 
-	while (loops--) {
+	do {
 		trdy = dz_in(dport, DZ_CSR);
 		if (!(trdy & DZ_TRDY))
 			continue;
@@ -697,7 +697,7 @@ static void dz_console_putchar(struct ua
 		dz_out(dport, DZ_TCR, mask);
 		iob();
 		udelay(2);
-	}
+	} while (loops--);
 
 	if (loops)				/* Cannot send otherwise. */
 		dz_out(dport, DZ_TDR, ch);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux