Merge tag 'char-misc-4.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregk...

[karo-tx-linux.git] / drivers / acpi / spcr.c

diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
index 4ac3e06b41d846440d35079dfa54885111eec0df..98aa8c808a3346dc559e2f419ae4378dec075ffc 100644 (file)
--- a/drivers/acpi/spcr.c
+++ b/drivers/acpi/spcr.c
@@ -16,6 +16,16 @@
 #include <linux/kernel.h>
 #include <linux/serial_core.h>
 
+/*
+ * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
+ * occasionally getting stuck as 1. To avoid the potential for a hang, check
+ * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
+ * implementations, so only do so if an affected platform is detected in
+ * parse_spcr().
+ */
+bool qdf2400_e44_present;
+EXPORT_SYMBOL(qdf2400_e44_present);
+
 /*
  * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
  * Detect them by examining the OEM fields in the SPCR header, similiar to PCI
@@ -147,8 +157,30 @@ int __init parse_spcr(bool earlycon)
                goto done;
        }
 
-       if (qdf2400_erratum_44_present(&table->header))
-               uart = "qdf2400_e44";
+       /*
+        * If the E44 erratum is required, then we need to tell the pl011
+        * driver to implement the work-around.
+        *
+        * The global variable is used by the probe function when it
+        * creates the UARTs, whether or not they're used as a console.
+        *
+        * If the user specifies "traditional" earlycon, the qdf2400_e44
+        * console name matches the EARLYCON_DECLARE() statement, and
+        * SPCR is not used.  Parameter "earlycon" is false.
+        *
+        * If the user specifies "SPCR" earlycon, then we need to update
+        * the console name so that it also says "qdf2400_e44".  Parameter
+        * "earlycon" is true.
+        *
+        * For consistency, if we change the console name, then we do it
+        * for everyone, not just earlycon.
+        */
+       if (qdf2400_erratum_44_present(&table->header)) {
+               qdf2400_e44_present = true;
+               if (earlycon)
+                       uart = "qdf2400_e44";
+       }
+
        if (xgene_8250_erratum_present(table))
                iotype = "mmio32";