[PATCH v3 resend 2/3] mmc: sdhci-acpi: Add blacklist module option

[Hans de Goede <hdegoede@redhat.com>]

Commit e5bbf30733f9 ("mmc: sdhci-acpi: Ensure connected devices are
powered when probing") introduced unconditional calling of
acpi_device_fix_up_power() on the mmc controller and its children.

This broke wifi on some systems because acpi_device_fix_up_power()
was called even for disabled children sometimes leaving gpio-s in
a state where wifi would not work, this was fixed in
commit e1d070c3793a ("mmc: sdhci-acpi: Only powered up enabled acpi
child devices").

Unfortunately on some devices calling acpi_device_fix_up_power()
still causes issues. Specifically on the GPD-win mini clam-shell PC
which has a pci-e wifi module, it causes the wifi module to get
turned off. This is a BIOS bug and I've tried to get the manufacturer
to fix this but sofar they have not responded (and even if they do
then we cannot assume all users will update their BIOS).

Since the GPD-win uses a pci-e wifi module the sdhci controller for
sdio cards really should not get initialized on it at all.

This commit adds a new sdhci_acpi.blacklist module option which can
be set to an ACPI hid:uid pair, e.g. "80860F14:2" to disable probing
for the sdhci host matching the hid:uid pair, fixing the wifi not
working on this machine.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
-Make the module option take a hid:uid pair string, instead of it
 being a boolean option, so that it only applies to one host
Changes in v3:
-Make the module option skip probing the device entirely (return -ENODEV)
---
 drivers/mmc/host/sdhci-acpi.c | 36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
index 89d9a8c014f5..3a7d979a306d 100644
--- a/drivers/mmc/host/sdhci-acpi.c
+++ b/drivers/mmc/host/sdhci-acpi.c
@@ -83,6 +83,29 @@ struct sdhci_acpi_host {
 	bool				use_runtime_pm;
 };
 
+static char *blacklist;
+
+static bool sdhci_acpi_compare_hid_uid(const char *match, const char *hid,
+				       const char *uid)
+{
+	const char *sep;
+
+	if (!match)
+		return false;
+
+	sep = strchr(match, ':');
+	if (!match)
+		return false;
+
+	if (strncmp(match, hid, sep - match))
+		return false;
+
+	if (strcmp(sep + 1, uid))
+		return false;
+
+	return true;
+}
+
 static inline bool sdhci_acpi_flag(struct sdhci_acpi_host *c, unsigned int flag)
 {
 	return c->slot && (c->slot->flags & flag);
@@ -378,6 +401,7 @@ static int sdhci_acpi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	acpi_handle handle = ACPI_HANDLE(dev);
+	const char *bl = blacklist;
 	struct acpi_device *device, *child;
 	struct sdhci_acpi_host *c;
 	struct sdhci_host *host;
@@ -390,6 +414,12 @@ static int sdhci_acpi_probe(struct platform_device *pdev)
 	if (acpi_bus_get_device(handle, &device))
 		return -ENODEV;
 
+	hid = acpi_device_hid(device);
+	uid = device->pnp.unique_id;
+
+	if (sdhci_acpi_compare_hid_uid(bl, hid, uid))
+		return -ENODEV;
+
 	/* Power on the SDHCI controller and its children */
 	acpi_device_fix_up_power(device);
 	list_for_each_entry(child, &device->children, node)
@@ -399,9 +429,6 @@ static int sdhci_acpi_probe(struct platform_device *pdev)
 	if (sdhci_acpi_byt_defer(dev))
 		return -EPROBE_DEFER;
 
-	hid = acpi_device_hid(device);
-	uid = device->pnp.unique_id;
-
 	iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!iomem)
 		return -ENOMEM;
@@ -580,6 +607,9 @@ static struct platform_driver sdhci_acpi_driver = {
 
 module_platform_driver(sdhci_acpi_driver);
 
+module_param(blacklist, charp, 0444);
+MODULE_PARM_DESC(blacklist, "ACPI <HID:UID> which should be ignored");
+
 MODULE_DESCRIPTION("Secure Digital Host Controller Interface ACPI driver");
 MODULE_AUTHOR("Adrian Hunter");
 MODULE_LICENSE("GPL v2");
-- 
2.13.0