[Mesa-dev] [PATCH 2/2] swr: Report format max_samples=1 to maintain support for "fake" msaa.

[Cherniak, Bruce]

Gentle bump.  This fixes mesa master for Kitware's VTK testing.

> On Aug 25, 2017, at 2:59 PM, Cherniak, Bruce <bruce.cherniak at intel.com> wrote:
> 
> Accompanying patch "st/mesa: only try to create 1x msaa surfaces for
> 'fake' msaa" requires driver to report max_samples=1 to enable "fake"
> msaa. Previously, 0 and 1 were treated equivalently in st_init_extensions()
> and either could enable "fake" msaa.
> 
> This patch raises the swr default msaa_max_count from 0 to 1, so that
> swr_is_format_supported will report max_samples=1.
> 
> Real msaa can still be enabled by exporting SWR_MSAA_MAX_COUNT with a
> pow2 value between 2 and 16.
> 
> This patch is necessary to prevent an OpenSWR regression resulting from
> the st/mesa patch.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102038
> ---
> src/gallium/drivers/swr/swr_screen.cpp | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/src/gallium/drivers/swr/swr_screen.cpp b/src/gallium/drivers/swr/swr_screen.cpp
> index 3287bc6fee..cc8d9955b8 100644
> --- a/src/gallium/drivers/swr/swr_screen.cpp
> +++ b/src/gallium/drivers/swr/swr_screen.cpp
> @@ -255,13 +255,13 @@ swr_get_param(struct pipe_screen *screen, enum pipe_cap param)
>       return 1;
> 
>    /* MSAA support
> -    * If user has explicitly set max_sample_count = 0 (via SWR_MSAA_MAX_COUNT)
> -    * then disable all MSAA support and go back to old caps. */
> +    * If user has explicitly set max_sample_count = 1 (via SWR_MSAA_MAX_COUNT)
> +    * then disable all MSAA support and go back to old (FAKE_SW_MSAA) caps. */
>    case PIPE_CAP_TEXTURE_MULTISAMPLE:
>    case PIPE_CAP_MULTISAMPLE_Z_RESOLVE:
> -      return swr_screen(screen)->msaa_max_count ? 1 : 0;
> +      return (swr_screen(screen)->msaa_max_count > 1) ? 1 : 0;
>    case PIPE_CAP_FAKE_SW_MSAA:
> -      return swr_screen(screen)->msaa_max_count ? 0 : 1;
> +      return (swr_screen(screen)->msaa_max_count > 1) ? 0 : 1;
> 
>       /* unsupported features */
>    case PIPE_CAP_ANISOTROPIC_FILTER:
> @@ -1079,22 +1079,22 @@ swr_validate_env_options(struct swr_screen *screen)
>       screen->client_copy_limit = client_copy_limit;
> 
>    /* XXX msaa under development, disable by default for now */
> -   screen->msaa_max_count = 0; /* was SWR_MAX_NUM_MULTISAMPLES; */
> +   screen->msaa_max_count = 1; /* was SWR_MAX_NUM_MULTISAMPLES; */
> 
>    /* validate env override values, within range and power of 2 */
> -   int msaa_max_count = debug_get_num_option("SWR_MSAA_MAX_COUNT", 0);
> -   if (msaa_max_count) {
> -      if ((msaa_max_count < 0) || (msaa_max_count > SWR_MAX_NUM_MULTISAMPLES)
> +   int msaa_max_count = debug_get_num_option("SWR_MSAA_MAX_COUNT", 1);
> +   if (msaa_max_count != 1) {
> +      if ((msaa_max_count < 1) || (msaa_max_count > SWR_MAX_NUM_MULTISAMPLES)
>             || !util_is_power_of_two(msaa_max_count)) {
>          fprintf(stderr, "SWR_MSAA_MAX_COUNT invalid: %d\n", msaa_max_count);
>          fprintf(stderr, "must be power of 2 between 1 and %d" \
> -                         " (or 0 to disable msaa)\n",
> +                         " (or 1 to disable msaa)\n",
>                SWR_MAX_NUM_MULTISAMPLES);
> -         msaa_max_count = 0;
> +         msaa_max_count = 1;
>       }
> 
>       fprintf(stderr, "SWR_MSAA_MAX_COUNT: %d\n", msaa_max_count);
> -      if (!msaa_max_count)
> +      if (msaa_max_count == 1)
>          fprintf(stderr, "(msaa disabled)\n");
> 
>       screen->msaa_max_count = msaa_max_count;
> -- 
> 2.11.0
>