Re: [PARPORT] Non-interrupting PIO for PPF and ECP modes

• Previous message: redbear: "[PARPORT] Problem creating device nodes"
• In reply to: Tom Perkins: "[PARPORT] Non-interrupting PIO for PPF and ECP modes"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Sat, Nov 24, 2001 at 07:48:47PM -0500, Tom Perkins wrote:

> 2.) Changing the mode to ECR_TST looks illegal -- Violates the rule that
> ECR_PS2 must be visited first? This code is the same for the
> ecp_write_block code. In the MS version of 1284 spec I thought a
> control single STROBE was used to stop transfer?

By the way, if you have a tested patch to fix this, it would be most
welcome..

> Is this correct and what should be used for compat_write_block?

Don't know.

Phil has suggested to me that we make it so that the inactivity
timeout only has effect when another device wants the port. The
relevant change would be this:

--- linux/drivers/parport/parport_pc.c.inactivity Tue Dec 4 11:14:29 2001
+++ linux/drivers/parport/parport_pc.c Tue Dec 4 11:17:12 2001
@@ -600,12 +600,6 @@
                         /* Can't yield the port. */
                         schedule ();
 
- /* Anyone else waiting for the port? */
- if (port->waithead) {
- printk (KERN_DEBUG "Somebody wants the port\n");
- break;
- }
-
                 if (ecrval & 0x02) {
                         /* FIFO is full. Wait for interrupt. */
 
@@ -615,7 +609,7 @@
                         ret = parport_wait_event (port, HZ);
                         if (ret < 0) break;
                         ret = 0;
- if (!time_before (jiffies, expire)) {
+ if (port->waithead && !time_before (jiffies, expire)) {
                                 /* Timed out. */
                                 printk (KERN_DEBUG "FIFO write timed out\n");
                                 break;
@@ -739,7 +733,7 @@
                 ret = parport_wait_event (port, HZ);
                 if (ret < 0) break;
                 ret = 0;
- if (!time_before (jiffies, expire)) {
+ if (port->waithead && !time_before (jiffies, expire)) {
                         /* Timed out. */
                         printk (KERN_DEBUG "DMA write timed out\n");
                         break;
@@ -762,12 +756,6 @@
                         /* Can't yield the port. */
                         schedule ();
 
- /* Anyone else waiting for the port? */
- if (port->waithead) {
- printk (KERN_DEBUG "Somebody wants the port\n");
- break;
- }
-
                 /* update for possible DMA residue ! */
                 buf -= count;
                 left += count;

Does that seem like a reasonable thing to do? It would the FIFO/DMA
problems go away for the common case of there being a single device on
the port.

Tim.
*/

• application/pgp-signature attachment: stored

-- To unsubscribe, send mail to: linux-parport-request@torque.net --
-- with the single word "unsubscribe" in the body of the message. --

• Next message: Kipp Cannon: "[PARPORT] multiple low-level drivers"
• Previous message: redbear: "[PARPORT] Problem creating device nodes"
• In reply to: Tom Perkins: "[PARPORT] Non-interrupting PIO for PPF and ECP modes"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

This archive was generated by hypermail 2b29 : Tue Dec 04 2001 - 06:20:16 EST