sna: Prefer backlight iface based on /sys/class/backlight/*/type

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 111 insertions, 41 deletions

diff --git a/src/sna/sna_display.c b/src/sna/sna_display.c
index 07ff607e..0d9e4741 100644
--- a/src/sna/sna_display.c
+++ b/src/sna/sna_display.c
@@ -34,8 +34,10 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <dirent.h>
 #include <errno.h>
 #include <poll.h>
+#include <ctype.h>
 
 #include <xorgVersion.h>
 #include <X11/Xatom.h>
@@ -91,7 +93,7 @@ struct sna_output {
         int panel_vdisplay;
 
         int dpms_mode;
-        const char *backlight_iface;
+        char *backlight_iface;
         int backlight_active_level;
         int backlight_max;
         struct list link;
@@ -104,28 +106,6 @@ static inline struct sna_crtc *to_sna_crtc(xf86CrtcPtr crtc)
 
 #define BACKLIGHT_CLASS "/sys/class/backlight"
 
-/*
- * List of available kernel interfaces in priority order
- */
-static const char *backlight_interfaces[] = {
-        "intel", /* prefer our own native backlight driver */
-        "asus-laptop",
-        "asus-nb-wmi",
-        "eeepc",
-        "thinkpad_screen",
-        "mbp_backlight",
-        "fujitsu-laptop",
-        "sony",
-        "samsung",
-        "acpi_video1", /* finally fallback to the generic acpi drivers */
-        "acpi_video0",
-        NULL,
-};
-/*
- * Must be long enough for BACKLIGHT_CLASS + '/' + longest in above table +
- * '/' + "max_backlight"
- */
-#define BACKLIGHT_PATH_LEN 80
 /* Enough for 10 digits of backlight + '\n' + '\0' */
 #define BACKLIGHT_VALUE_LEN 12
 
@@ -219,14 +199,14 @@ static void
 sna_output_backlight_set(xf86OutputPtr output, int level)
 {
         struct sna_output *sna_output = output->driver_private;
-        char path[BACKLIGHT_PATH_LEN], val[BACKLIGHT_VALUE_LEN];
+        char path[1024], val[BACKLIGHT_VALUE_LEN];
         int fd, len, ret;
 
         DBG(("%s: level=%d\n", __FUNCTION__, level));
 
         if (level > sna_output->backlight_max)
                 level = sna_output->backlight_max;
-        if (! sna_output->backlight_iface || level < 0)
+        if (!sna_output->backlight_iface || level < 0)
                 return;
 
         len = snprintf(val, BACKLIGHT_VALUE_LEN, "%d\n", level);
@@ -252,7 +232,7 @@ static int
 sna_output_backlight_get(xf86OutputPtr output)
 {
         struct sna_output *sna_output = output->driver_private;
-        char path[BACKLIGHT_PATH_LEN], val[BACKLIGHT_VALUE_LEN];
+        char path[1024], val[BACKLIGHT_VALUE_LEN];
         int fd, level;
 
         sprintf(path, "%s/%s/actual_brightness",
@@ -287,7 +267,7 @@ static int
 sna_output_backlight_get_max(xf86OutputPtr output)
 {
         struct sna_output *sna_output = output->driver_private;
-        char path[BACKLIGHT_PATH_LEN], val[BACKLIGHT_VALUE_LEN];
+        char path[1024], val[BACKLIGHT_VALUE_LEN];
         int fd, max = 0;
 
         sprintf(path, "%s/%s/max_brightness",
@@ -313,29 +293,117 @@ sna_output_backlight_get_max(xf86OutputPtr output)
         return max;
 }
 
+enum {
+        FIRMWARE,
+        PLATFORM,
+        RAW,
+        NAMED,
+};
+
 static void
 sna_output_backlight_init(xf86OutputPtr output)
 {
+        static const char *known_interfaces[] = {
+                "asus-laptop",
+                "asus-nb-wmi",
+                "eeepc",
+                "thinkpad_screen",
+                "mbp_backlight",
+                "fujitsu-laptop",
+                "sony",
+                "samsung",
+                "acpi_video1",
+                "acpi_video0",
+                "intel_backlight",
+        };
         struct sna_output *sna_output = output->driver_private;
-        int i;
+        char *best_iface;
+        int best_type;
+        DIR *dir;
+        struct dirent *de;
+
+        best_iface = NULL;
+        best_type = INT_MAX;
+
+        dir = opendir(BACKLIGHT_CLASS);
+        while ((de = readdir(dir))) {
+                char path[1024];
+                char buf[100];
+                int fd, v;
+
+                snprintf(path, sizeof(path), "%s/%s/type",
+                         BACKLIGHT_CLASS, de->d_name);
+
+                v = -1;
+                fd = open(path, O_RDONLY);
+                if (fd >= 0) {
+                        v = read(fd, buf, sizeof(buf)-1);
+                        close(fd);
+                }
+                if (v > 0) {
+                        while (v > 0 && isspace(buf[v-1]))
+                                v--;
+                        buf[v] = '\0';
+
+                        if (strcmp(buf, "raw") == 0)
+                                v = RAW;
+                        else if (strcmp(buf, "platform") == 0)
+                                v = PLATFORM;
+                        else if (strcmp(buf, "firmware") == 0)
+                                v = FIRMWARE;
+                        else
+                                v = NAMED;
+                } else
+                        v = NAMED;
+
+                /* Fallback to priority list of known iface for old kernels */
+                if (v == NAMED) {
+                        int i;
+                        for (i = 0; i < ARRAY_SIZE(known_interfaces); i++) {
+                                if (strcmp(de->d_name, known_interfaces[i]) == 0)
+                                        break;
+                        }
+                        v += i;
+                }
+
+                if (v < best_type) {
+                        char *copy;
+                        int max;
+
+                        /* XXX detect right backlight for multi-GPU/panels */
+
+                        sna_output->backlight_iface = de->d_name;
+                        max = sna_output_backlight_get_max(output);
+                        if (max <= 0)
+                                continue;
 
-        for (i = 0; backlight_interfaces[i] != NULL; i++) {
-                char path[BACKLIGHT_PATH_LEN];
-                struct stat buf;
-
-                sprintf(path, "%s/%s", BACKLIGHT_CLASS, backlight_interfaces[i]);
-                if (!stat(path, &buf)) {
-                        sna_output->backlight_iface = backlight_interfaces[i];
-                        sna_output->backlight_max = sna_output_backlight_get_max(output);
-                        if (sna_output->backlight_max > 0) {
-                                sna_output->backlight_active_level = sna_output_backlight_get(output);
-                                xf86DrvMsg(output->scrn->scrnIndex, X_INFO,
-                                           "found backlight control interface %s\n", path);
-                                return;
+                        copy = strdup(de->d_name);
+                        if (copy) {
+                                free(best_iface);
+                                best_iface = copy;
+                                best_type = v;
                         }
                 }
         }
+
         sna_output->backlight_iface = NULL;
+
+        if (best_iface) {
+                const char *str;
+
+                sna_output->backlight_iface = best_iface;
+                sna_output->backlight_max = sna_output_backlight_get_max(output);
+                sna_output->backlight_active_level = sna_output_backlight_get(output);
+                switch (best_type) {
+                case FIRMWARE: str = "firmware"; break;
+                case PLATFORM: str = "platform"; break;
+                case RAW: str = "raw"; break;
+                default: str = "unknown"; break;
+                }
+                xf86DrvMsg(output->scrn->scrnIndex, X_INFO,
+                           "found backlight control interface %s (type '%s')\n",
+                           best_iface, str);
+        }
 }
 
 
@@ -1515,6 +1583,8 @@ sna_output_destroy(xf86OutputPtr output)
         drmModeFreeConnector(sna_output->mode_output);
         sna_output->mode_output = NULL;
 
+        free(sna_output->backlight_iface);
+
         list_del(&sna_output->link);
         free(sna_output);