Re: [Qemu-devel] [PATCH] Parallel Port Direction Fix

[Aurelien Jarno]

On Tue, Jun 10, 2008 at 05:20:15PM +0530, Vijay Kumar wrote:
> The direction bit in the control register should not be directly
> set using PPWCONTROL. The kernel gives the following debug message.
>
>    parport0 (ppdev0): use data_reverse for this!
>
> More over setting the data pins to forward mode does not work,
> perhaps a bug in the Linux PP driver. The right way to do this is
> to use PPDATADIR to set the direction. The patch checks if the
> user is toggling the direction bit, and invokes PPDATADIR to
> do the job.

Applied, thanks.

> Signed-off-by: Vijay Kumar B <address@hidden>
> ---
> diff -Naur qemu-orig/hw/parallel.c qemu-mod/hw/parallel.c
> --- qemu-orig/hw/parallel.c   2008-06-10 16:58:10.000000000 +0530
> +++ qemu-mod/hw/parallel.c    2008-06-10 16:47:23.000000000 +0530
> @@ -129,6 +129,7 @@
> {
>     ParallelState *s = opaque;
>     uint8_t parm = val;
> +    int dir;
>
>     /* Sometimes programs do several writes for timing purposes on old
>        HW. Take care not to waste time on writes that do nothing. */
> @@ -154,6 +155,17 @@
>         if (s->control == val)
>             return;
>         pdebug("wc%02x\n", val);
> +
> +        if ((val & PARA_CTR_DIR) != (s->control & PARA_CTR_DIR)) {
> +            if (val & PARA_CTR_DIR) {
> +                dir = 1;
> +            } else {
> +                dir = 0;
> +            }
> +            qemu_chr_ioctl(s->chr, CHR_IOCTL_PP_DATA_DIR, &dir);
> +            parm &= ~PARA_CTR_DIR;
> +        }
> +
>         qemu_chr_ioctl(s->chr, CHR_IOCTL_PP_WRITE_CONTROL, &parm);
>         s->control = val;
>         break;
> diff -Naur qemu-orig/qemu-char.h qemu-mod/qemu-char.h
> --- qemu-orig/qemu-char.h     2008-06-10 16:58:10.000000000 +0530
> +++ qemu-mod/qemu-char.h      2008-06-10 16:39:24.000000000 +0530
> @@ -27,6 +27,7 @@
> #define CHR_IOCTL_PP_EPP_READ         9
> #define CHR_IOCTL_PP_EPP_WRITE_ADDR  10
> #define CHR_IOCTL_PP_EPP_WRITE       11
> +#define CHR_IOCTL_PP_DATA_DIR        12
>
> typedef void IOEventHandler(void *opaque, int event);
>
> diff -Naur qemu-orig/vl.c qemu-mod/vl.c
> --- qemu-orig/vl.c    2008-06-10 16:58:10.000000000 +0530
> +++ qemu-mod/vl.c     2008-06-10 16:39:24.000000000 +0530
> @@ -2525,6 +2525,10 @@
>             return -ENOTSUP;
>         *(uint8_t *)arg = b;
>         break;
> +    case CHR_IOCTL_PP_DATA_DIR:
> +        if (ioctl(fd, PPDATADIR, (int *)arg) < 0)
> +            return -ENOTSUP;
> +        break;
>     case CHR_IOCTL_PP_EPP_READ_ADDR:
>       if (pp_hw_mode(drv, IEEE1284_MODE_EPP|IEEE1284_ADDR)) {
>           struct ParallelIOArg *parg = arg;
>
>
>

-- 
  .''`.  Aurelien Jarno             | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   address@hidden         | address@hidden
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