drm/i915: Expand force_probe to block probe of devices as well.

There are new cases where we want to block i915 probe, such
as when experimenting or developing the new Xe driver.

But also, with the new hybrid cards, users or developers might
want to use i915 only on integrated and fully block the probe
of the i915 for the discrete. Or vice versa.

There are even older development and validation reasons,
like when you use some distro where the modprobe.blacklist is
not present.

But in any case, let's introduce a more granular control, but without
introducing yet another parameter, but using the existent force_probe
one.

Just by adding a ! in the begin of the id in the force_probe, like
in this case where we would block the probe for Alder Lake:

$ insmod i915.ko force_probe='!46a6'

v2: Take care of '*' and  '!*' cases as pointed out by
    Gustavo and Jani.

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230103194701.1492984-1-rodrigo.vivi@intel.com

1 files changed, 28 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
index a65802b252f2..0f3e0ce416f8 100644
--- a/drivers/gpu/drm/i915/i915_pci.c
+++ b/drivers/gpu/drm/i915/i915_pci.c
@@ -1253,7 +1253,7 @@ static void i915_pci_remove(struct pci_dev *pdev)
 }
 
 /* is device_id present in comma separated list of ids */
-static bool force_probe(u16 device_id, const char *devices)
+static bool device_id_in_list(u16 device_id, const char *devices, bool negative)
 {
 	char *s, *p, *tok;
 	bool ret;
@@ -1262,7 +1262,9 @@ static bool force_probe(u16 device_id, const char *devices)
 		return false;
 
 	/* match everything */
-	if (strcmp(devices, "*") == 0)
+	if (negative && strcmp(devices, "!*") == 0)
+		return true;
+	if (!negative && strcmp(devices, "*") == 0)
 		return true;
 
 	s = kstrdup(devices, GFP_KERNEL);
@@ -1272,6 +1274,12 @@ static bool force_probe(u16 device_id, const char *devices)
 	for (p = s, ret = false; (tok = strsep(&p, ",")) != NULL; ) {
 		u16 val;
 
+		if (negative && tok[0] == '!')
+			tok++;
+		else if ((negative && tok[0] != '!') ||
+			 (!negative && tok[0] == '!'))
+			continue;
+
 		if (kstrtou16(tok, 16, &val) == 0 && val == device_id) {
 			ret = true;
 			break;
@@ -1283,6 +1291,16 @@ static bool force_probe(u16 device_id, const char *devices)
 	return ret;
 }
 
+static bool id_forced(u16 device_id)
+{
+	return device_id_in_list(device_id, i915_modparams.force_probe, false);
+}
+
+static bool id_blocked(u16 device_id)
+{
+	return device_id_in_list(device_id, i915_modparams.force_probe, true);
+}
+
 bool i915_pci_resource_valid(struct pci_dev *pdev, int bar)
 {
 	if (!pci_resource_flags(pdev, bar))
@@ -1308,10 +1326,9 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		(struct intel_device_info *) ent->driver_data;
 	int err;
 
-	if (intel_info->require_force_probe &&
-	    !force_probe(pdev->device, i915_modparams.force_probe)) {
+	if (intel_info->require_force_probe && !id_forced(pdev->device)) {
 		dev_info(&pdev->dev,
-			 "Your graphics device %04x is not properly supported by the driver in this\n"
+			 "Your graphics device %04x is not properly supported by i915 in this\n"
 			 "kernel version. To force driver probe anyway, use i915.force_probe=%04x\n"
 			 "module parameter or CONFIG_DRM_I915_FORCE_PROBE=%04x configuration option,\n"
 			 "or (recommended) check for kernel updates.\n",
@@ -1319,6 +1336,12 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		return -ENODEV;
 	}
 
+	if (id_blocked(pdev->device)) {
+		dev_info(&pdev->dev, "I915 probe blocked for Device ID %04x.\n",
+			 pdev->device);
+		return -ENODEV;
+	}
+
 	/* Only bind to function 0 of the device. Early generations
 	 * used function 1 as a placeholder for multi-head. This causes
 	 * us confusion instead, especially on the systems where both