On the Acer Switch Alpha 12 (model number: SA5-271), the internal SSD may not get detected because the port_map and CAP.nr_ports combination causes the driver to skip the port that is actually connected to the SSD. This problem occurs occasionally. When this problem occurs, CAP may hold a value of 0xC734FF00 or 0xC734FF01 and port_map may hold a value of 0x00 or 0x01. When this problem does not occur, CAP holds a value of 0xC734FF02 and port_map may hold a value of 0x07. Overriding the CAP value to 0xC734FF02 and port_map to 0x7 noticeably reduces the occurrences of this problem. Link: https://bugzilla.kernel.org/attachment.cgi?id=253091 Signed-off-by: Sui Chen <suichen6@xxxxxxxxx> Tested-by: Damian Ivanov <damianatorrpm@xxxxxxxxx> --- diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c index 2fc5240..6b29e64 100644 --- a/drivers/ata/ahci.c +++ b/drivers/ata/ahci.c @@ -1364,6 +1364,39 @@ static inline void ahci_gtf_filter_workaround(struct ata_host *host) {} #endif +/* + * On the Acer Aspire Switch Alpha 12, sometimes all SATA channels + * are detected as DUMMY. When this happens, the last byte of the CAP + * register becomes 0x00 or 0x01, wrongly indicating there are only + * 1 or 2 SATA channels in the system. + * + * Overriding the last byte in the CAP register to 0x02 (which + * indicates to 3 channels) resolves this problem. + * + * https://bugzilla.kernel.org/show_bug.cgi?id=189471 + */ +static void acpi_sa5_271_workaround(struct ahci_host_priv *hpriv, + struct pci_dev *pdev) +{ + static const struct dmi_system_id sysids[] = { + { + .ident = "Acer Switch Alpha 12", + .matches = { + DMI_MATCH(DMI_SYS_VENDOR, "Acer"), + DMI_MATCH(DMI_PRODUCT_NAME, "Switch SA5-271") + }, + }, + { } + }; + if (true || dmi_check_system(sysids)) { + dev_info(&pdev->dev, "enabling Acer Switch Alpha 12 workaround\n"); + if ((hpriv->saved_cap & 0xC734FF00) == 0xC734FF00) { + hpriv->port_map = 0x7; + hpriv->cap = 0xC734FF02; + } + } +} + #ifdef CONFIG_ARM64 /* * Due to ERRATA#22536, ThunderX needs to handle HOST_IRQ_STAT differently. @@ -1636,6 +1669,10 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) "online status unreliable, applying workaround\n"); } + + /* Acer SA5-271 workaround modifies private_data */ + acpi_sa5_271_workaround(hpriv, pdev); + /* CAP.NP sometimes indicate the index of the last enabled * port, at other times, that of the last possible port, so * determining the maximum port number requires looking at -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
