diff mbox series

[v3] fdc/i8257: implement verify transfer mode

Message ID 20191101165513.14229-1-svens@stackframe.org (mailing list archive)
State New, archived
Headers show
Series [v3] fdc/i8257: implement verify transfer mode | expand

Commit Message

Sven Schnelle Nov. 1, 2019, 4:55 p.m. UTC 
While working on the Tulip driver i tried to write some Teledisk images to
a floppy image which didn't work. Turned out that Teledisk checks the written
data by issuing a READ command to the FDC but running the DMA controller
in VERIFY mode. As we ignored the DMA request in that case, the DMA transfer
never finished, and Teledisk reported an error.

The i8257 spec says about verify transfers:

3) DMA verify, which does not actually involve the transfer of data. When an
8257 channel is in the DMA verify mode, it will respond the same as described
for transfer operations, except that no memory or I/O read/write control signals
will be generated.

Hervé proposed to remove all the dma_mode_ok stuff from fdc to have a more
clear boundary between DMA and FDC, so this patch also does that.

Suggested-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 hw/block/fdc.c       | 61 +++++++++++++-------------------------------
 hw/dma/i8257.c       | 20 ++++++++++-----
 include/hw/isa/isa.h |  1 -
 3 files changed, 31 insertions(+), 51 deletions(-)

Comments

Hervé Poussineau Nov. 3, 2019, 9:53 p.m. UTC | #1 
Le 01/11/2019 à 17:55, Sven Schnelle a écrit :
> While working on the Tulip driver i tried to write some Teledisk images to
> a floppy image which didn't work. Turned out that Teledisk checks the written
> data by issuing a READ command to the FDC but running the DMA controller
> in VERIFY mode. As we ignored the DMA request in that case, the DMA transfer
> never finished, and Teledisk reported an error.
> 
> The i8257 spec says about verify transfers:
> 
> 3) DMA verify, which does not actually involve the transfer of data. When an
> 8257 channel is in the DMA verify mode, it will respond the same as described
> for transfer operations, except that no memory or I/O read/write control signals
> will be generated.
> 
> Hervé proposed to remove all the dma_mode_ok stuff from fdc to have a more
> clear boundary between DMA and FDC, so this patch also does that.
> 
> Suggested-by: Hervé Poussineau <hpoussin@reactos.org>
> Signed-off-by: Sven Schnelle <svens@stackframe.org>
> ---
>   hw/block/fdc.c       | 61 +++++++++++++-------------------------------
>   hw/dma/i8257.c       | 20 ++++++++++-----
>   include/hw/isa/isa.h |  1 -
>   3 files changed, 31 insertions(+), 51 deletions(-)

Reviewed-by: Hervé Poussineau <hpoussin@reactos.org>
John Snow March 18, 2020, 10:28 p.m. UTC | #2 
On 11/1/19 12:55 PM, Sven Schnelle wrote:
> While working on the Tulip driver i tried to write some Teledisk images to
> a floppy image which didn't work. Turned out that Teledisk checks the written
> data by issuing a READ command to the FDC but running the DMA controller
> in VERIFY mode. As we ignored the DMA request in that case, the DMA transfer
> never finished, and Teledisk reported an error.
> 
> The i8257 spec says about verify transfers:
> 
> 3) DMA verify, which does not actually involve the transfer of data. When an
> 8257 channel is in the DMA verify mode, it will respond the same as described
> for transfer operations, except that no memory or I/O read/write control signals
> will be generated.
> 
> Hervé proposed to remove all the dma_mode_ok stuff from fdc to have a more
> clear boundary between DMA and FDC, so this patch also does that.
> 
> Suggested-by: Hervé Poussineau <hpoussin@reactos.org>
> Signed-off-by: Sven Schnelle <svens@stackframe.org>

I know it's many many moons later; I was out of the country for a month
when this patch arrived, and I lost track of it under my email backlog.

It looks reviewed and good to go, so I am staging it locally and testing it.

Thanks,
--js
diff mbox series

Patch

diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index ac5d31e8c1..01812c7553 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -1714,53 +1714,28 @@  static void fdctrl_start_transfer(FDCtrl *fdctrl, int direction)
     }
     fdctrl->eot = fdctrl->fifo[6];
     if (fdctrl->dor & FD_DOR_DMAEN) {
-        IsaDmaTransferMode dma_mode;
+        /* DMA transfer is enabled. */
         IsaDmaClass *k = ISADMA_GET_CLASS(fdctrl->dma);
-        bool dma_mode_ok;
-        /* DMA transfer are enabled. Check if DMA channel is well programmed */
-        dma_mode = k->get_transfer_mode(fdctrl->dma, fdctrl->dma_chann);
-        FLOPPY_DPRINTF("dma_mode=%d direction=%d (%d - %d)\n",
-                       dma_mode, direction,
-                       (128 << fdctrl->fifo[5]) *
+
+        FLOPPY_DPRINTF("direction=%d (%d - %d)\n",
+                       direction, (128 << fdctrl->fifo[5]) *
                        (cur_drv->last_sect - ks + 1), fdctrl->data_len);
-        switch (direction) {
-        case FD_DIR_SCANE:
-        case FD_DIR_SCANL:
-        case FD_DIR_SCANH:
-            dma_mode_ok = (dma_mode == ISADMA_TRANSFER_VERIFY);
-            break;
-        case FD_DIR_WRITE:
-            dma_mode_ok = (dma_mode == ISADMA_TRANSFER_WRITE);
-            break;
-        case FD_DIR_READ:
-            dma_mode_ok = (dma_mode == ISADMA_TRANSFER_READ);
-            break;
-        case FD_DIR_VERIFY:
-            dma_mode_ok = true;
-            break;
-        default:
-            dma_mode_ok = false;
-            break;
-        }
-        if (dma_mode_ok) {
-            /* No access is allowed until DMA transfer has completed */
-            fdctrl->msr &= ~FD_MSR_RQM;
-            if (direction != FD_DIR_VERIFY) {
-                /* Now, we just have to wait for the DMA controller to
-                 * recall us...
-                 */
-                k->hold_DREQ(fdctrl->dma, fdctrl->dma_chann);
-                k->schedule(fdctrl->dma);
-            } else {
-                /* Start transfer */
-                fdctrl_transfer_handler(fdctrl, fdctrl->dma_chann, 0,
-                                        fdctrl->data_len);
-            }
-            return;
+
+        /* No access is allowed until DMA transfer has completed */
+        fdctrl->msr &= ~FD_MSR_RQM;
+        if (direction != FD_DIR_VERIFY) {
+            /*
+             * Now, we just have to wait for the DMA controller to
+             * recall us...
+             */
+            k->hold_DREQ(fdctrl->dma, fdctrl->dma_chann);
+            k->schedule(fdctrl->dma);
         } else {
-            FLOPPY_DPRINTF("bad dma_mode=%d direction=%d\n", dma_mode,
-                           direction);
+            /* Start transfer */
+            fdctrl_transfer_handler(fdctrl, fdctrl->dma_chann, 0,
+                    fdctrl->data_len);
         }
+        return;
     }
     FLOPPY_DPRINTF("start non-DMA transfer\n");
     fdctrl->msr |= FD_MSR_NONDMA | FD_MSR_RQM;
diff --git a/hw/dma/i8257.c b/hw/dma/i8257.c
index 792f617eb4..85dad3d391 100644
--- a/hw/dma/i8257.c
+++ b/hw/dma/i8257.c
@@ -292,12 +292,6 @@  static uint64_t i8257_read_cont(void *opaque, hwaddr nport, unsigned size)
     return val;
 }
 
-static IsaDmaTransferMode i8257_dma_get_transfer_mode(IsaDma *obj, int nchan)
-{
-    I8257State *d = I8257(obj);
-    return (d->regs[nchan & 3].mode >> 2) & 3;
-}
-
 static bool i8257_dma_has_autoinitialization(IsaDma *obj, int nchan)
 {
     I8257State *d = I8257(obj);
@@ -400,6 +394,11 @@  static void i8257_dma_register_channel(IsaDma *obj, int nchan,
     r->opaque = opaque;
 }
 
+static bool i8257_is_verify_transfer(I8257Regs *r)
+{
+    return (r->mode & 0x0c) == 0;
+}
+
 static int i8257_dma_read_memory(IsaDma *obj, int nchan, void *buf, int pos,
                                  int len)
 {
@@ -407,6 +406,10 @@  static int i8257_dma_read_memory(IsaDma *obj, int nchan, void *buf, int pos,
     I8257Regs *r = &d->regs[nchan & 3];
     hwaddr addr = ((r->pageh & 0x7f) << 24) | (r->page << 16) | r->now[ADDR];
 
+    if (i8257_is_verify_transfer(r)) {
+        return len;
+    }
+
     if (r->mode & 0x20) {
         int i;
         uint8_t *p = buf;
@@ -431,6 +434,10 @@  static int i8257_dma_write_memory(IsaDma *obj, int nchan, void *buf, int pos,
     I8257Regs *r = &s->regs[nchan & 3];
     hwaddr addr = ((r->pageh & 0x7f) << 24) | (r->page << 16) | r->now[ADDR];
 
+    if (i8257_is_verify_transfer(r)) {
+        return len;
+    }
+
     if (r->mode & 0x20) {
         int i;
         uint8_t *p = buf;
@@ -597,7 +604,6 @@  static void i8257_class_init(ObjectClass *klass, void *data)
     dc->vmsd = &vmstate_i8257;
     dc->props = i8257_properties;
 
-    idc->get_transfer_mode = i8257_dma_get_transfer_mode;
     idc->has_autoinitialization = i8257_dma_has_autoinitialization;
     idc->read_memory = i8257_dma_read_memory;
     idc->write_memory = i8257_dma_write_memory;
diff --git a/include/hw/isa/isa.h b/include/hw/isa/isa.h
index 018ada4f6f..f516e253c5 100644
--- a/include/hw/isa/isa.h
+++ b/include/hw/isa/isa.h
@@ -56,7 +56,6 @@  typedef int (*IsaDmaTransferHandler)(void *opaque, int nchan, int pos,
 typedef struct IsaDmaClass {
     InterfaceClass parent;
 
-    IsaDmaTransferMode (*get_transfer_mode)(IsaDma *obj, int nchan);
     bool (*has_autoinitialization)(IsaDma *obj, int nchan);
     int (*read_memory)(IsaDma *obj, int nchan, void *buf, int pos, int len);
     int (*write_memory)(IsaDma *obj, int nchan, void *buf, int pos, int len);