On 09.11.2016 19:08, Emil Velikov wrote:
From: Emil Velikov <emil.velikov@xxxxxxxxxxxxx>
Parsing config sysfs file wakes up the device. The latter of which may
be slow and isn't required to begin with.
Reading through config is/was required since the revision is not
available by other means, although with a kernel patch in the way that
is about to change.
Since returning 0 when one might expect a valid value is a no-go add a
workaround drmDeviceUseRevisionFile() which one can use to say "I don't
care if the revision file returns 0."
v2: Complete rework - add new API to control the method, instead of
changing it underneat the users' feet.
Cc: Michel Dänzer <michel.daenzer@xxxxxxx>
Cc: Mauro Santos <registo.mailling@xxxxxxxxx>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98502
Signed-off-by: Emil Velikov <emil.velikov@xxxxxxxxxxxxx>
---
I don't have a strong preference for/against this or v1.
With this Mesa will require a 2 line patch. With v1 things will get
fixed magically, when rebuilt against newer libdrm.
Mauro I'll send the mesa patch in a second. Feel free to give it a spin.
Thanks
---
xf86drm.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
xf86drm.h | 11 ++++++++++
2 files changed, 78 insertions(+), 3 deletions(-)
diff --git a/xf86drm.c b/xf86drm.c
index 52add5e..676effc 100644
--- a/xf86drm.c
+++ b/xf86drm.c
@@ -113,6 +113,13 @@ void drmSetServerInfo(drmServerInfoPtr info)
drm_server_info = info;
}
+static bool use_revision_file;
+
+void drmDeviceUseRevisionFile(void)
+{
+ use_revision_file = true;
+}
I think this API of setting a magic hidden global variable is really nasty.
Can we add new drmGetDevice[s] entry points with a flags parameter and a
flag (per Michel's suggestion) which says "I don't care about the
revision ID"? It kind of sucks because they'll have to get a silly name
like drmGetDevice[s]2, but I think that's still better than magic global
state.
Cheers,
Nicolai
+
/**
* Output a message to stderr.
*
@@ -2946,10 +2953,56 @@ static int drmGetMaxNodeName(void)
3 /* length of the node number */;
}
-static int drmParsePciDeviceInfo(const char *d_name,
- drmPciDeviceInfoPtr device)
-{
#ifdef __linux__
+static int parse_separate_sysfs_files(const char *d_name,
+ drmPciDeviceInfoPtr device)
+{
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
+ static const char *attrs[] = {
+ "revision", /* XXX: make sure it's always first, see note below */
+ "vendor",
+ "device",
+ "subsystem_vendor",
+ "subsystem_device",
+ };
+ char path[PATH_MAX + 1];
+ unsigned int data[ARRAY_SIZE(attrs)];
+ FILE *fp;
+ int ret;
+
+ for (unsigned i = 0; i < ARRAY_SIZE(attrs); i++) {
+ snprintf(path, PATH_MAX, "/sys/class/drm/%s/device/%s",
+ d_name, attrs[i]);
+ fp = fopen(path, "r");
+ if (!fp) {
+ /* Note: First we check the revision, since older kernels
+ * may not have it. Default to zero in such cases. */
+ if (i == 0) {
+ data[i] = 0;
+ continue;
+ }
+ return -errno;
+ }
+
+ ret = fscanf(fp, "%x", &data[i]);
+ fclose(fp);
+ if (ret != 1)
+ return -errno;
+
+ }
+
+ device->revision_id = data[0] & 0xff;
+ device->vendor_id = data[1] & 0xffff;
+ device->device_id = data[2] & 0xffff;
+ device->subvendor_id = data[3] & 0xffff;
+ device->subdevice_id = data[4] & 0xffff;
+
+ return 0;
+}
+
+static int parse_config_sysfs_file(const char *d_name,
+ drmPciDeviceInfoPtr device)
+{
char path[PATH_MAX + 1];
unsigned char config[64];
int fd, ret;
@@ -2971,6 +3024,17 @@ static int drmParsePciDeviceInfo(const char *d_name,
device->subdevice_id = config[46] | (config[47] << 8);
return 0;
+}
+#endif
+
+static int drmParsePciDeviceInfo(const char *d_name,
+ drmPciDeviceInfoPtr device)
+{
+#ifdef __linux__
+ if (use_revision_file)
+ return parse_separate_sysfs_files(d_name, device);
+
+ return parse_config_sysfs_file(d_name, device);
#else
#warning "Missing implementation of drmParsePciDeviceInfo"
return -EINVAL;
diff --git a/xf86drm.h b/xf86drm.h
index 481d882..d1ebc32 100644
--- a/xf86drm.h
+++ b/xf86drm.h
@@ -796,6 +796,17 @@ extern void drmFreeDevice(drmDevicePtr *device);
extern int drmGetDevices(drmDevicePtr devices[], int max_devices);
extern void drmFreeDevices(drmDevicePtr devices[], int count);
+
+/**
+ * Force any sequential calls to drmGetDevice/drmGetDevices to use the
+ * revision sysfs file instead of config one. The latter wakes up the device
+ * if powered off.
+ *
+ * A value of 0 will be returned for the revision_id field if the sysfs file
+ * is missing. DO NOT USE THIS if you depend on a correct revision_id.
+ */
+extern void drmDeviceUseRevisionFile(void);
+
#if defined(__cplusplus)
}
#endif
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