[PATCH 1/3] mmc: sdhci-pci: disable aggressive runtime PM for Braswell SD on Lenovo N22

[Nelson Johnson <nzjfr547@gmail.com>]

Lenovo N22 systems with the Braswell SD controller (PCI ID 8086:2296) regress on kernels newer than 4.9. On this machine the SD slot is exposed through both PCI and ACPI firmware nodes, and enabling the newer aggressive runtime PM/card-detect wake path causes the controller to stop behaving like the older working configuration.

Keep the Lenovo N22 on the pre-4.14 behavior by skipping MMC_CAP_AGGRESSIVE_PM and MMC_CAP_CD_WAKE for the 8086:2296 slot on this DMI match, and disable runtime PM for that host.

This preserves the rest of the Braswell/Atom handling while restoring the power-management behavior that allows the slot to function on the Lenovo N22.

Fixes: 6cf4156c0988 ("mmc: sdhci-pci: Enable card detect wake for Intel BYT-related SD controllers")
Signed-off-by: Nelson Johnson <nzjfr547@gmail.com>
---
 drivers/mmc/host/sdhci-pci-core.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index 47a0a7388..4b3c61609 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -923,6 +923,13 @@ static bool jsl_broken_hs400es(struct sdhci_pci_slot *slot)
 			dmi_match(DMI_BIOS_VENDOR, "ASUSTeK COMPUTER INC.");
 }
 
+static bool sdhci_pci_is_lenovo_n22_bsw_sd(struct sdhci_pci_slot *slot)
+{
+	return slot->chip->pdev->device == PCI_DEVICE_ID_INTEL_BSW_SD &&
+	       dmi_match(DMI_SYS_VENDOR, "LENOVO") &&
+	       dmi_match(DMI_BOARD_NAME, "N22");
+}
+
 static int glk_emmc_probe_slot(struct sdhci_pci_slot *slot)
 {
 	int ret = byt_emmc_probe_slot(slot);
@@ -1120,9 +1127,13 @@ static void byt_needs_pwr_off(struct sdhci_pci_slot *slot)
 
 static int byt_sd_probe_slot(struct sdhci_pci_slot *slot)
 {
+	bool runtime_pm_ok = !sdhci_pci_is_lenovo_n22_bsw_sd(slot);
+
 	byt_probe_slot(slot);
-	slot->host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY |
-				 MMC_CAP_AGGRESSIVE_PM | MMC_CAP_CD_WAKE;
+	slot->host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
+	if (runtime_pm_ok)
+		slot->host->mmc->caps |= MMC_CAP_AGGRESSIVE_PM |
+					 MMC_CAP_CD_WAKE;
 	slot->cd_idx = 0;
 	slot->cd_override_level = true;
 	if (slot->chip->pdev->device == PCI_DEVICE_ID_INTEL_BXT_SD ||
@@ -1135,7 +1146,10 @@ static int byt_sd_probe_slot(struct sdhci_pci_slot *slot)
 	    slot->chip->pdev->subsystem_device == PCI_SUBDEVICE_ID_NI_78E3)
 		slot->host->mmc->caps2 |= MMC_CAP2_AVOID_3_3V;
 
-	byt_needs_pwr_off(slot);
+	if (runtime_pm_ok)
+		byt_needs_pwr_off(slot);
+	else
+		slot->chip->allow_runtime_pm = false;
 
 	return 0;
 }
-- 
2.47.3