[PATCH xserver 2/2] xf86RandR12: Fix XF86VidModeSetGamma triggering a BadImplementation error

[Hans de Goede]

Commit b4e46c0444bb ("xfree86: Hook up colormaps and RandR 1.2 gamma code")
dropped the providing of a pScrn->ChangeGamma callback from the xf86RandR12
code. Leaving pScrn->ChangeGamma NULL in most cases.

This triggers the BadImplementation error in xf86ChangeGamma() :

    if (pScrn->ChangeGamma)
        return (*pScrn->ChangeGamma) (pScrn, gamma);

    return BadImplementation;

Which causes X-apps using XF86VidModeSetGamma to crash with a
X protocol error.

This commit fixes this by re-introducing the xf86RandR12ChangeGamma
helper removed by the commit and adjusting it to work with the new
combined palette / gamma code.

Fixes: b4e46c0444bb ("xfree86: Hook up colormaps and RandR 1.2 gamma code")
Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 hw/xfree86/modes/xf86RandR12.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/hw/xfree86/modes/xf86RandR12.c b/hw/xfree86/modes/xf86RandR12.c
index 36767b3..7b3b97b 100644
--- a/hw/xfree86/modes/xf86RandR12.c
+++ b/hw/xfree86/modes/xf86RandR12.c
@@ -1916,6 +1916,34 @@ xf86RandR12LoadPalette(ScrnInfoPtr pScrn, int numColors, int *indices,
     }
 }
 
+/*
+ * Compatibility with XF86VidMode's gamma changer.  This necessarily clobbers
+ * any per-crtc setup.  You asked for it...
+ */
+
+static int
+xf86RandR12ChangeGamma(ScrnInfoPtr pScrn, Gamma gamma)
+{
+    RRCrtcPtr randr_crtc = xf86CompatRRCrtc(pScrn);
+    int size;
+
+    if (!randr_crtc)
+        return Success;
+
+    size = max(0, randr_crtc->gammaSize);
+    if (!size)
+        return Success;
+
+    init_one_component(randr_crtc->gammaRed, size, gamma.red);
+    init_one_component(randr_crtc->gammaGreen, size, gamma.green);
+    init_one_component(randr_crtc->gammaBlue, size, gamma.blue);
+    xf86RandR12CrtcSetGamma(xf86ScrnToScreen(pScrn), randr_crtc);
+
+    pScrn->gamma = gamma;
+
+    return Success;
+}
+
 static Bool
 xf86RandR12EnterVT(ScrnInfoPtr pScrn)
 {
@@ -2115,6 +2143,7 @@ xf86RandR12Init12(ScreenPtr pScreen)
     rp->rrProviderDestroy = xf86RandR14ProviderDestroy;
 
     pScrn->PointerMoved = xf86RandR12PointerMoved;
+    pScrn->ChangeGamma = xf86RandR12ChangeGamma;
 
     randrp->orig_EnterVT = pScrn->EnterVT;
     pScrn->EnterVT = xf86RandR12EnterVT;
-- 
2.9.3