Re: [PATCH 14/15] ide: rework the code for selecting the best DMA transfer mode

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Sergei Shtylyov wrote:

Hello.

Bartlomiej Zolnierkiewicz wrote:
[PATCH] ide: rework the code for selecting the best DMA transfer mode 



Depends on the "ide: fix UDMA/MWDMA/SWDMA masks" patch.



  I'm now trying to rewrite hpt366.c to benefit more from these patches...
and alas, this very patch seems to be breaking filtering (at least) in this driver. :-] 


Index: b/drivers/ide/ide-dma.c
===================================================================
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -705,6 +705,80 @@ int ide_use_dma(ide_drive_t *drive)
EXPORT_SYMBOL_GPL(ide_use_dma); +static const u8 xfer_mode_bases[] = { 
+    XFER_UDMA_0,
+    XFER_MW_DMA_0,
+    XFER_SW_DMA_0,
+};
+
+static unsigned int ide_get_mode_mask(ide_drive_t *drive, u8 base)
+{
+    struct hd_driveid *id = drive->id;
+    ide_hwif_t *hwif = drive->hwif;
+    unsigned int mask = 0;
+
+    switch(base) {
+    case XFER_UDMA_0:
+        if ((id->field_valid & 4) == 0)
+            break;
+
+        mask = id->dma_ultra & hwif->ultra_mask;
+
+        if (hwif->udma_filter)
+            mask &= hwif->udma_filter(drive);
+
+        if ((mask & 0x78) && (eighty_ninty_three(drive) == 0))
+            mask &= 0x07;
Note the subtle difference between the old and new behavior: the old driver code was applying UltraDMA filter *after* 
the cable type limit, and the new code does it *before*.


  Was there any particular reason to change that order?

[...]


Index: b/drivers/ide/pci/hpt366.c
===================================================================
--- a/drivers/ide/pci/hpt366.c
+++ b/drivers/ide/pci/hpt366.c
@@ -513,43 +513,31 @@ static int check_in_drive_list(ide_drive
     return 0;
 }
-static u8 hpt3xx_ratemask(ide_drive_t *drive) 
-{
-    struct hpt_info *info    = pci_get_drvdata(HWIF(drive)->pci_dev);
-    u8 mode            = info->max_mode;
-
-    if (!eighty_ninty_three(drive) && mode)
-        mode = min(mode, (u8)1);
-    return mode;
-}
-
 /*
  *    Note for the future; the SATA hpt37x we must set
  *    either PIO or UDMA modes 0,4,5
  */
- -static u8 hpt3xx_ratefilter(ide_drive_t *drive, u8 speed)
+
+static u8 hpt3xx_udma_filter(ide_drive_t *drive)
 {
     struct hpt_info *info    = pci_get_drvdata(HWIF(drive)->pci_dev);
     u8 chip_type        = info->chip_type;
-    u8 mode            = hpt3xx_ratemask(drive);
-
-    if (drive->media != ide_disk)
-        return min(speed, (u8)XFER_PIO_4);
+    u8 mode            = info->max_mode;
+    u8 mask;
switch (mode) { 
         case 0x04:
-            speed = min_t(u8, speed, XFER_UDMA_6);
+            mask = 0x7f;
             break;
         case 0x03:
-            speed = min_t(u8, speed, XFER_UDMA_5);
+            mask = 0x3f;
             if (chip_type >= HPT374)
                 break;
             if (!check_in_drive_list(drive, bad_ata100_5))
                 goto check_bad_ata33;
             /* fall thru */
         case 0x02:
-            speed = min_t(u8, speed, XFER_UDMA_4);
+            mask = 0x1f;
/* 
              * CHECK ME, Does this need to be changed to HPT374 ??
@@ -560,13 +548,13 @@ static u8 hpt3xx_ratefilter(ide_drive_t !check_in_drive_list(drive, bad_ata66_4)) 
                 goto check_bad_ata33;
- speed = min_t(u8, speed, XFER_UDMA_3); 
+            mask = 0x0f;
             if (HPT366_ALLOW_ATA66_3 &&
                 !check_in_drive_list(drive, bad_ata66_3))
                 goto check_bad_ata33;
             /* fall thru */
         case 0x01:
-            speed = min_t(u8, speed, XFER_UDMA_2);
+            mask = 0x07;
check_bad_ata33: 
             if (chip_type >= HPT370A)
This case 0x01 will *never* be hit for HPT370 chip with the new code, therefore the filter won't get applied. 

  Oh, and for HPT36x chips used with 40c cable too (unless they're artificaially reduced to UltraDMA/33 by the driver #define's).
@@ -576,10 +564,10 @@ static u8 hpt3xx_ratefilter(ide_drive_t /* fall thru */ 
         case 0x00:
         default:
-            speed = min_t(u8, speed, XFER_MW_DMA_2);
+            mask = 0x00;
             break;


  Well, that case 0x00 should never actually happen.


     }
-    return speed;
+    return mask;
 }


[...]


@@ -1270,6 +1272,7 @@ static void __devinit init_hwif_hpt366(i
     hwif->intrproc            = &hpt3xx_intrproc;
     hwif->maskproc            = &hpt3xx_maskproc;
     hwif->busproc            = &hpt3xx_busproc;
+    hwif->udma_filter        = &hpt3xx_udma_filter;
In fact, we only need a filter for HPT36x/370 chips -- I'll address it in my patch. 


     /*
      * HPT3xxN chips have some complications:


MBR, Sergei

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