[PATCH v2 3/3] mmc: sdhci-pci: only install voltage switch method when useful

From: Anisse Astier
Date: Tue Oct 23 2018 - 06:07:50 EST


If there's no ACPI DSM for voltage switch, it will just cause a lot of
debug info down the line, we only need one at startup.

Signed-off-by: Anisse Astier <anisse@xxxxxxxxx>
---
drivers/mmc/host/sdhci-pci-core.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index f2c1fb339d66..95fdbb883c7e 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -723,6 +723,7 @@ static const struct dmi_system_id board_no_1_8v[] = {
static void byt_probe_slot(struct sdhci_pci_slot *slot)
{
struct mmc_host_ops *ops = &slot->host->mmc_host_ops;
+ struct intel_host *intel_host = sdhci_pci_priv(slot);

byt_read_dsm(slot);

@@ -733,6 +734,16 @@ static void byt_probe_slot(struct sdhci_pci_slot *slot)
mmc_hostname(slot->host->mmc));
slot->host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
}
+ /* Check if we have the appropriate voltage switch DSM methods */
+ if (!(intel_host->dsm_fns & (1 << INTEL_DSM_V18_SWITCH)) &&
+ !(intel_host->dsm_fns & (1 << INTEL_DSM_V33_SWITCH))) {
+ /* No voltage switching supported at all, there's no
+ * point in installing the callback: return.
+ */
+ pr_debug("%s: No voltage switching ACPI DSM helper\n",
+ mmc_hostname(slot->host->mmc));
+ return;
+ }
ops->start_signal_voltage_switch = intel_start_signal_voltage_switch;
}

--
2.17.2