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Re: [Qemu-devel] [PATCH 3/3] ide/via: Implement and use native PCI IDE m

From: BALATON Zoltan
Subject: Re: [Qemu-devel] [PATCH 3/3] ide/via: Implement and use native PCI IDE mode
Date: Thu, 24 Jan 2019 03:23:55 +0100 (CET)
User-agent: Alpine 2.21.9999 (BSF 287 2018-06-16)

On Wed, 23 Jan 2019, John Snow wrote:
On 1/22/19 7:39 AM, BALATON Zoltan wrote:
The device was initialised in ISA compatibility mode and native PCI
IDE mode was not implemented but no clents are known to need ISA mode
but to the contrary, most clients that want to switch to and use
device in native PCI IDE mode. Therefore implement native PCI mode and
switch default to that.

Signed-off-by: BALATON Zoltan <address@hidden>
 hw/ide/via.c | 52 ++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 38 insertions(+), 14 deletions(-)

diff --git a/hw/ide/via.c b/hw/ide/via.c
index c6e43a8812..ac9385228c 100644
--- a/hw/ide/via.c
+++ b/hw/ide/via.c
@@ -32,15 +32,6 @@
 #include "hw/ide/pci.h"
 #include "trace.h"

-static const struct {
-    int iobase;
-    int iobase2;
-    int isairq;
-} port_info[] = {
-    {0x1f0, 0x3f6, 14},
-    {0x170, 0x376, 15},
 static uint64_t bmdma_read(void *opaque, hwaddr addr,
                            unsigned size)
@@ -110,6 +101,23 @@ static void bmdma_setup_bar(PCIIDEState *d)

+static void via_ide_set_irq(void *opaque, int n, int level)
+    PCIDevice *d = PCI_DEVICE(opaque);
+    if (level) {
+        d->config[0x70 + n * 8] |= 0x80;
+    } else {
+        d->config[0x70 + n * 8] &= ~0x80;
+    }
+    level = (d->config[0x70] & 0x80) || (d->config[0x78] & 0x80);
+    n = pci_get_byte(d->config + PCI_INTERRUPT_LINE);
+    if (n) {
+        qemu_set_irq(isa_get_irq(NULL, n), level);
+    }
 static void via_ide_reset(void *opaque)
     PCIIDEState *d = opaque;
@@ -121,7 +129,7 @@ static void via_ide_reset(void *opaque)

-    pci_set_word(pci_conf + PCI_COMMAND, PCI_COMMAND_WAIT);
+    pci_set_word(pci_conf + PCI_COMMAND, PCI_COMMAND_IO | PCI_COMMAND_WAIT);
     pci_set_word(pci_conf + PCI_STATUS, PCI_STATUS_FAST_BACK |

@@ -158,10 +166,28 @@ static void via_ide_realize(PCIDevice *dev, Error **errp)
     uint8_t *pci_conf = dev->config;
     int i;

-    pci_config_set_prog_interface(pci_conf, 0x8a); /* legacy ATA mode */
+    pci_config_set_prog_interface(pci_conf, 0x8f); /* native PCI ATA mode */
     pci_set_long(pci_conf + PCI_CAPABILITY_LIST, 0x000000c0);
+    dev->wmask[PCI_INTERRUPT_LINE] = 0xf;

     qemu_register_reset(via_ide_reset, d);
+    memory_region_init_io(&d->data_bar[0], OBJECT(d), &pci_ide_data_le_ops,
+                          &d->bus[0], "via-ide0-data", 8);
+    pci_register_bar(dev, 0, PCI_BASE_ADDRESS_SPACE_IO, &d->data_bar[0]);
+    memory_region_init_io(&d->cmd_bar[0], OBJECT(d), &pci_ide_cmd_le_ops,
+                          &d->bus[0], "via-ide0-cmd", 4);
+    pci_register_bar(dev, 1, PCI_BASE_ADDRESS_SPACE_IO, &d->cmd_bar[0]);
+    memory_region_init_io(&d->data_bar[1], OBJECT(d), &pci_ide_data_le_ops,
+                          &d->bus[1], "via-ide1-data", 8);
+    pci_register_bar(dev, 2, PCI_BASE_ADDRESS_SPACE_IO, &d->data_bar[1]);
+    memory_region_init_io(&d->cmd_bar[1], OBJECT(d), &pci_ide_cmd_le_ops,
+                          &d->bus[1], "via-ide1-cmd", 4);
+    pci_register_bar(dev, 3, PCI_BASE_ADDRESS_SPACE_IO, &d->cmd_bar[1]);
     pci_register_bar(dev, 4, PCI_BASE_ADDRESS_SPACE_IO, &d->bmdma_bar);

@@ -169,9 +195,7 @@ static void via_ide_realize(PCIDevice *dev, Error **errp)

     for (i = 0; i < 2; i++) {
         ide_bus_new(&d->bus[i], sizeof(d->bus[i]), DEVICE(d), i, 2);
-        ide_init_ioport(&d->bus[i], NULL, port_info[i].iobase,
-                        port_info[i].iobase2);
-        ide_init2(&d->bus[i], isa_get_irq(NULL, port_info[i].isairq));
+        ide_init2(&d->bus[i], qemu_allocate_irq(via_ide_set_irq, d, i));

         bmdma_init(&d->bus[i], &d->bmdma[i], d);
         d->bmdma[i].bus = &d->bus[i];

I guess this is technically an external change in behavior... I have no
real read on if this will break anything for anyone, or if anyone was
even using it.

Currently nothing but the mips_fulong2e board seems to use this device and I don't think there's anything even on that board that would depend on (or would work with) legacy only IDE mode of this device but I could not find a test image to try. That board seems to be quite unfinished, I've tried to get it in better shape but haven't succeeded yet. So I don't think this change in the IDE device would break anything for anyone as it does not seem to be usable yet but I plan to use this IDE part in subsequent patches and PCI native mode works better.

Any thoughts on why it's okay to switch?

As said above it's unlikely anyone would depend on it now and all drivers I know about prefer native mode anyway so likely it would work better after this change. If not and it turns out someone is using the current behaviour I can look at implementing switching between the two modes but that would be more difficult (the ISA ports would need to be mapped and unmapped based on bits in PCI_PROG_INTERFACE but there's no API to do this currently, ide/core.c only has ide_init_ioport to add mapping but not the counterpart to remove it; this could be implemented but unless found to be needed it probably does not worth it). So I suggest to switch based on that this is a quite unused part that's not likely to break anything and if it still found to break something I'll look at fixing it or it could be reverted, but I don't want to spend time now on something that's not actually used.


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