Enable framebuffer compression (use Option "FrameBufferCompression"

"true" in your xorg.conf).  Should save ~0.5W during typical 2D usage.

5 files changed, 171 insertions, 2 deletions

diff --git a/man/intel.man b/man/intel.man
index 89916194..3e443cd2 100644
--- a/man/intel.man
+++ b/man/intel.man
@@ -77,6 +77,13 @@ driver attempts to allocate space for at 3 screenfuls of pixmaps plus an
 HD-sized XV video.  The default used for a specific configuration can be found
 by examining the __xservername__ log file.
 .TP
+.BI "Option \*qFrameBufferCompression\*q \*q" boolean \*q
+This option controls whether the framebuffer compression feature is enabled.
+If possible, the front buffer will be allocated in a tiled format and compressed
+periodically to save memory bandwidth and power.
+.TP
+This option is only available on mobile chipsets.
+.TP
 .BI "Option \*qDRI\*q \*q" boolean \*q
 Disable or enable DRI support.
 Default: DRI is enabled for configurations where it is supported.
diff --git a/src/i830.h b/src/i830.h
index 9dda33a7..29982ecd 100644
--- a/src/i830.h
+++ b/src/i830.h
@@ -287,6 +287,8 @@ typedef struct _I830Rec {
 
    i830_memory *front_buffer;
    i830_memory *front_buffer_2;
+   i830_memory *compressed_front_buffer;
+   i830_memory *compressed_ll_buffer;
    /* One big buffer for all cursors for kernels that support this */
    i830_memory *cursor_mem;
    /* separate small buffers for kernels that support this */
@@ -342,6 +344,7 @@ typedef struct _I830Rec {
    Bool allowPageFlip;
    Bool TripleBuffer;
    Bool disableTiling;
+   Bool fb_compression;
 
    int backPitch;
 
diff --git a/src/i830_display.c b/src/i830_display.c
index aba86ae7..f3b24b20 100644
--- a/src/i830_display.c
+++ b/src/i830_display.c
@@ -653,15 +653,110 @@ i830_crtc_unlock (xf86CrtcPtr crtc)
 #endif
 }
 
+#define FBC_CFB_BASE		0x03200 /* 4k page aligned */
+#define FBC_LL_BASE		0x03204 /* 4k page aligned */
+#define FBC_CONTROL		0x03208
+#define   FBC_CTL_EN		(1<<31)
+#define   FBC_CTL_PERIODIC	(1<<30)
+#define   FBC_CTL_INTERVAL_SHIFT (16)
+#define   FBC_CTL_STRIDE_SHIFT	(5)
+#define   FBC_CTL_FENCENO	(1<<0)
+#define FBC_COMMAND		0x0320c
+#define   FBC_CMD_COMPRESS	(1<<0)
+#define FBC_STATUS		0x03210
+#define   FBC_STAT_COMPRESSING	(1<<31)
+#define   FBC_STAT_COMPRESSED	(1<<30)
+#define   FBC_STAT_MODIFIED	(1<<29)
+#define   FBC_STAT_CURRENT_LINE	(1<<0)
+#define FBC_CONTROL2		0x03214
+#define   FBC_CTL_CPU_FENCE	(1<<1)
+#define   FBC_CTL_PIPEA		(0<<0)
+#define   FBC_CTL_PIPEB		(1<<0)
+
+#define FBC_COMPRESSED_LINES	(1536+32)
+
+/*
+ * Several restrictions:
+ *   - DSP[AB]CNTR - no line duplication && no pixel multiplier
+ *   - pixel format == 15 bit, 16 bit, or 32 bit xRGB_8888
+ *   - no alpha buffer discard
+ *   - no dual wide display
+ *   - progressive mode only (DSP[AB]CNTR)
+ *
+ * FIXME: verify above conditions are true
+ */
+static void
+i830_enable_fb_compression(xf86CrtcPtr crtc)
+{
+    ScrnInfoPtr pScrn = crtc->scrn;
+    I830Ptr pI830 = I830PTR(pScrn);
+    I830CrtcPrivatePtr	intel_crtc = crtc->driver_private;
+    uint32_t fbc_ctl;
+    unsigned long compressed_stride;
+    int pipe = intel_crtc->pipe;
+    int plane = (pipe == 0 ? FBC_CTL_PIPEA : FBC_CTL_PIPEB);
+    unsigned long uncompressed_stride = pScrn->displayWidth * pI830->cpp;
+    unsigned long interval = 1000;
+
+    compressed_stride = pI830->compressed_front_buffer->size /
+	FBC_COMPRESSED_LINES;
+
+    if (uncompressed_stride < compressed_stride)
+	compressed_stride = uncompressed_stride;
+
+    /* FBC_CTL wants 64B units */
+    compressed_stride = (compressed_stride / 64) - 1;
+
+    /* Set it up... */
+    OUTREG(FBC_CFB_BASE, pI830->compressed_front_buffer->bus_addr);
+    OUTREG(FBC_LL_BASE, pI830->compressed_ll_buffer->bus_addr);
+    OUTREG(FBC_CONTROL2, FBC_CTL_CPU_FENCE | plane);
+
+    /* enable it... */
+    fbc_ctl = INREG(FBC_CONTROL);
+    fbc_ctl |= FBC_CTL_EN | FBC_CTL_PERIODIC;
+    fbc_ctl |= (compressed_stride & 0xff) << FBC_CTL_STRIDE_SHIFT;
+    fbc_ctl |= (interval & 0x2fff) << FBC_CTL_INTERVAL_SHIFT;
+    OUTREG(FBC_CONTROL, fbc_ctl);
+
+    /* and request immediate compression */
+    OUTREG(FBC_COMMAND, FBC_CMD_COMPRESS);
+}
+
+static void
+i830_disable_fb_compression(xf86CrtcPtr crtc)
+{
+    ScrnInfoPtr pScrn = crtc->scrn;
+    I830Ptr pI830 = I830PTR(pScrn);
+    uint32_t fbc_ctl;
+
+    /* Disable compression */
+    fbc_ctl = INREG(FBC_CONTROL);
+    fbc_ctl &= ~FBC_CTL_EN;
+    OUTREG(FBC_CONTROL, fbc_ctl);
+
+    /* Wait for compressing bit to clear */
+    while (INREG(FBC_STATUS) & FBC_STAT_COMPRESSING)
+	; /* nothing */
+}
+
 static void
 i830_crtc_prepare (xf86CrtcPtr crtc)
 {
+    ScrnInfoPtr pScrn = crtc->scrn;
+    I830Ptr pI830 = I830PTR(pScrn);
     crtc->funcs->dpms (crtc, DPMSModeOff);
+
+    /* Temporarily turn off FB compression during modeset */
+    if (pI830->fb_compression)
+	i830_disable_fb_compression(crtc);
 }
 
 static void
 i830_crtc_commit (xf86CrtcPtr crtc)
 {
+    ScrnInfoPtr pScrn = crtc->scrn;
+    I830Ptr pI830 = I830PTR(pScrn);
     I830CrtcPrivatePtr	intel_crtc = crtc->driver_private;
     Bool		deactivate = FALSE;
 
@@ -675,6 +770,10 @@ i830_crtc_commit (xf86CrtcPtr crtc)
 	xf86_reload_cursors (crtc->scrn->pScreen);
     if (deactivate)
 	i830_pipe_a_require_deactivate (crtc->scrn);
+
+    /* Reenable FB compression if possible */
+    if (pI830->fb_compression)
+	i830_enable_fb_compression(crtc);
 }
 
 void
diff --git a/src/i830_driver.c b/src/i830_driver.c
index 7f1fe2cc..42d0f872 100644
--- a/src/i830_driver.c
+++ b/src/i830_driver.c
@@ -285,6 +285,7 @@ typedef enum {
    OPTION_COLOR_KEY,
    OPTION_CHECKDEVICES,
    OPTION_MODEDEBUG,
+   OPTION_FBC,
 #ifdef XF86DRI_MM
    OPTION_INTELTEXPOOL,
    OPTION_INTELMMSIZE,
@@ -306,6 +307,7 @@ static OptionInfoRec I830Options[] = {
    {OPTION_VIDEO_KEY,	"VideoKey",	OPTV_INTEGER,	{0},	FALSE},
    {OPTION_CHECKDEVICES, "CheckDevices",OPTV_BOOLEAN,	{0},	FALSE},
    {OPTION_MODEDEBUG,	"ModeDebug",	OPTV_BOOLEAN,	{0},	FALSE},
+   {OPTION_FBC,		"FrameBufferCompression", OPTV_BOOLEAN, {0}, FALSE},
 #ifdef XF86DRI_MM
    {OPTION_INTELTEXPOOL,"Legacy3D",     OPTV_BOOLEAN,	{0},	FALSE},
    {OPTION_INTELMMSIZE, "AperTexSize",  OPTV_INTEGER,	{0},	FALSE},
@@ -2305,6 +2307,11 @@ I830ScreenInit(int scrnIndex, ScreenPtr pScreen, int argc, char **argv)
       pI830->CacheLines = -1;
    }
 
+   if (xf86ReturnOptValBool(pI830->Options, OPTION_FBC, FALSE))
+       pI830->fb_compression = TRUE;
+   else
+       pI830->fb_compression = FALSE;
+
    pI830->disableTiling = FALSE;
 
    if (I830IsPrimary(pScrn)) {
diff --git a/src/i830_memory.c b/src/i830_memory.c
index afdd93d7..5e553f18 100644
--- a/src/i830_memory.c
+++ b/src/i830_memory.c
@@ -902,8 +902,8 @@ i830_allocate_framebuffer(ScrnInfoPtr pScrn, I830Ptr pI830, BoxPtr FbMemBox,
     name = secondary ? "secondary front buffer" : "front buffer";
 
     /* Attempt to allocate it tiled first if we have page flipping on. */
-    if (!pI830->disableTiling && pI830->allowPageFlip &&
-	IsTileable(pScrn, pitch))
+    if ((!pI830->disableTiling && pI830->allowPageFlip &&
+	 IsTileable(pScrn, pitch)) || pI830->fb_compression)
     {
 	/* XXX: probably not the case on 965 */
 	if (IS_I9XX(pI830))
@@ -1022,6 +1022,56 @@ i830_allocate_cursor_buffers(ScrnInfoPtr pScrn)
     return TRUE;
 }
 
+static void i830_setup_fb_compression(ScrnInfoPtr pScrn)
+{
+    I830Ptr pI830 = I830PTR(pScrn);
+
+    /* Only mobile chips since 845 support this feature */
+    if (!IS_MOBILE(pI830)) {
+	pI830->fb_compression = FALSE;
+	goto out;
+    }
+
+    /*
+     * Compressed framebuffer limitations:
+     *   - contiguous, physical, uncached memory
+     *   - ideally as large as the front buffer(s), smaller sizes cache less
+     *   - uncompressed buffer must be tiled w/pitch 2k-16k
+     *   - uncompressed fb is <= 2048 in width, 0 mod 8
+     *   - uncompressed fb is <= 1536 in height, 0 mod 2
+     *   - compressed fb stride is <= uncompressed stride
+     *   - SR display watermarks must be equal between 16bpp and 32bpp?
+     *   - both compressed and line buffers must be in stolen memory
+     */
+    pI830->compressed_front_buffer =
+	i830_allocate_memory(pScrn, "compressed frame buffer",
+			     MB(6), KB(4),
+			     NEED_PHYSICAL_ADDR);
+
+    if (!pI830->compressed_front_buffer) {
+	pI830->fb_compression = FALSE;
+	goto out;
+    }
+
+    pI830->compressed_ll_buffer =
+	i830_allocate_memory(pScrn, "compressed ll buffer",
+			     1568, KB(4), NEED_PHYSICAL_ADDR);
+    if (!pI830->compressed_ll_buffer) {
+	i830_free_memory(pScrn, pI830->compressed_front_buffer);
+	pI830->fb_compression = FALSE;
+	goto out;
+    }
+
+out:
+    if (pI830->fb_compression)
+	xf86DrvMsg(pScrn->scrnIndex, X_INFO, "Framebuffer compression "
+		   "enabled\n");
+    else
+	xf86DrvMsg(pScrn->scrnIndex, X_WARNING, "Allocation error, framebuffer"
+		   " compression disabled\n");
+	
+    return;
+}
 /*
  * Allocate memory for 2D operation.  This includes the (front) framebuffer,
  * ring buffer, scratch memory, HW cursor.
@@ -1046,6 +1096,9 @@ i830_allocate_2d_memory(ScrnInfoPtr pScrn)
     /* Allocate the ring buffer first, so it ends up in stolen mem. */
     i830_allocate_ringbuffer(pScrn);
 
+    if (pI830->fb_compression)
+	i830_setup_fb_compression(pScrn);
+
     /* Next, allocate other fixed-size allocations we have. */
     if (!pI830->SWCursor && !i830_allocate_cursor_buffers(pScrn)) {
 	xf86DrvMsg(pScrn->scrnIndex, X_WARNING,