Hello.

Tejun Heo wrote:

Okay, here's another try at fixing the detection bug.  I went through
intel ich docs and compared with the ide piix driver.  This patch
fixes the following problems.

diff --git a/drivers/ata/ata_piix.c b/drivers/ata/ata_piix.c
index c6bf1a3..51f55a0 100644
--- a/drivers/ata/ata_piix.c
+++ b/drivers/ata/ata_piix.c
@@ -728,8 +728,14 @@ static void piix_set_piomode (struct ata_port *ap, struct 
ata_device *adev)
        if (adev->class == ATA_DEV_ATA)
                control |= 4;   /* PPE enable */
+ /* PIO configuration clears DTE unconditionally. It will be
+        * programmed in set_dmamode which is guaranteed to be called
+        * after set_piomode if any DMA mode is available.
+        */

Actually, I think ata_timing_merge() should just be performed when setting MWDMA mode... This should be the right thing to do in most cases (however, this hardware has some complications in the form of only 2-bit wide active/recovery counts and 2 fast timing bank select bits)...

        pci_read_config_word(dev, master_port, &master_data);
        if (is_slave) {
+               /* clear TIME1|IE1|PPE1|DTE1 */
+               master_data &= 0xff0f;

   Yeah, I've fixed this oversight in piix.c...

                /* Enable SITRE (seperate slave timing register) */
                master_data |= 0x4000;
                /* enable PPE1, IE1 and TIME1 as needed */
@@ -737,12 +743,14 @@ static void piix_set_piomode (struct ata_port *ap, struct 
ata_device *adev)
                pci_read_config_byte(dev, slave_port, &slave_data);
                slave_data &= (ap->port_no ? 0x0f : 0xf0);
                /* Load the timing nibble for this slave */
-               slave_data |= ((timings[pio][0] << 2) | timings[pio][1]) << 
(ap->port_no ? 4 : 0);
+               slave_data |= ((timings[pio][0] << 2) | timings[pio][1])
+                                               << (ap->port_no ? 4 : 0);
        } else {
-               /* Master keeps the bits in a different format */
-               master_data &= 0xccf8;
+               /* clear ISP|RCT|TIME0|IE0|PPE0|DTE0 */
+               master_data &= 0xccf0;
                /* Enable PPE, IE and TIME as appropriate */
                master_data |= control;
+               /* load ISP and RCT */
                master_data |=
                        (timings[pio][0] << 12) |
                        (timings[pio][1] << 8);
@@ -859,7 +867,7 @@ static void do_pata_set_dmamode (struct ata_port *ap, 
struct ata_device *adev, i
                        master_data &= 0xFF4F;  /* Mask out IORDY|TIME1|DMAONLY 
*/
                        master_data |= control << 4;
                        pci_read_config_byte(dev, 0x44, &slave_data);
-                       slave_data &= (0x0F + 0xE1 * ap->port_no);
+                       slave_data &= (ap->port_no ? 0x0f : 0xf0);
                        /* Load the matching timing */
                        slave_data |= ((timings[pio][0] << 2) | timings[pio][1]) 
<< (ap->port_no ? 4 : 0);
                        pci_write_config_byte(dev, 0x44, slave_data);
@@ -871,8 +879,11 @@ static void do_pata_set_dmamode (struct ata_port *ap, 
struct ata_device *adev, i
                                (timings[pio][0] << 12) |
                                (timings[pio][1] << 8);
                }
-               udma_enable &= ~(1 << devid);
-               pci_write_config_word(dev, master_port, master_data);
+
+               if (ap->udma_mask) {
+                       udma_enable &= ~(1 << devid);
+                       pci_write_config_word(dev, master_port, master_data);
+               }

I've also noticed that this is done at the end of piix_set_piomode() and I see no reason why. Isn't it just a leftover from the piix.c brokenness? This driver coupled PIO and UDMA timing updates for no conceivable reason?

MBR, Sergei
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