Below you'll find the part of the AMD Elan patch which deals with a bug in
the processor-integrated serial interface.
The code was discussed with Theodore Ts'o and Russell King - tytso wanted
to send it to Marcelo afterwards, but nothing happened so far, so here's
the patch, against 2.4.18.
Thx,
Robert
-- +--------------------------------------------------------+ | Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de | | Pengutronix - Linux Solutions for Science and Industry | | Braunschweiger Str. 79, 31134 Hildesheim, Germany | | Phone: +49-5121-28619-0 | Fax: +49-5121-28619-4 | +--------------------------------------------------------+diff -urN -X kernel-patches/dontdiff linux-2.4.18/drivers/char/serial.c linux-2.4.18-elan/drivers/char/serial.c --- linux-2.4.18/drivers/char/serial.c Mon Feb 25 20:37:57 2002 +++ linux-2.4.18-elan/drivers/char/serial.c Tue Feb 26 09:58:39 2002 @@ -57,6 +57,11 @@ * 10/00: add in optional software flow control for serial console. * Kanoj Sarcar <kanoj@sgi.com> (Modified by Theodore Ts'o) * + * 02/02: Fix for AMD Elan bug in transmit irq routine, by + * Christer Weinigel <wingel@hog.ctrl-c.liu.se>, + * Robert Schwebel <robert@schwebel.de>, + * Juergen Beisert <jbeisert@eurodsn.de>, + * Theodore Ts'o <tytso@mit.edu> */
static char *serial_version = "5.05c"; @@ -801,7 +806,7 @@ */ static void rs_interrupt(int irq, void *dev_id, struct pt_regs * regs) { - int status; + int status, iir; struct async_struct * info; int pass_counter = 0; struct async_struct *end_mark = 0; @@ -826,7 +831,7 @@
do { if (!info->tty || - (serial_in(info, UART_IIR) & UART_IIR_NO_INT)) { + ((iir=serial_in(info, UART_IIR)) & UART_IIR_NO_INT)) { if (!end_mark) end_mark = info; goto next; @@ -845,7 +850,9 @@ if (status & UART_LSR_DR) receive_chars(info, &status, regs); check_modem_status(info); - if (status & UART_LSR_THRE) + if ((status & UART_LSR_THRE) || + /* for buggy ELAN processors */ + ((iir & UART_IIR_ID) == UART_IIR_THRI)) transmit_chars(info, 0);
next: @@ -879,7 +886,7 @@ */ static void rs_interrupt_single(int irq, void *dev_id, struct pt_regs * regs) { - int status; + int status, iir; int pass_counter = 0; struct async_struct * info; #ifdef CONFIG_SERIAL_MULTIPORT @@ -901,6 +908,7 @@ first_multi = inb(multi->port_monitor); #endif
+ iir = serial_in(info, UART_IIR); do { status = serial_inp(info, UART_LSR); #ifdef SERIAL_DEBUG_INTR @@ -909,18 +917,21 @@ if (status & UART_LSR_DR) receive_chars(info, &status, regs); check_modem_status(info); - if (status & UART_LSR_THRE) + if ((status & UART_LSR_THRE) || + /* For buggy ELAN processors */ + ((iir & UART_IIR_ID) == UART_IIR_THRI)) transmit_chars(info, 0); if (pass_counter++ > RS_ISR_PASS_LIMIT) { -#if 0 +#if SERIAL_DEBUG_INTR printk("rs_single loop break.\n"); #endif break; } + iir = serial_in(info, UART_IIR); #ifdef SERIAL_DEBUG_INTR - printk("IIR = %x...", serial_in(info, UART_IIR)); + printk("IIR = %x...", iir); #endif - } while (!(serial_in(info, UART_IIR) & UART_IIR_NO_INT)); + } while ((iir & UART_IIR_NO_INT) == 0); info->last_active = jiffies; #ifdef CONFIG_SERIAL_MULTIPORT if (multi->port_monitor)
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This archive was generated by hypermail 2b29 : Thu Feb 28 2002 - 21:00:41 EST