On 12/13/2017 06:45 AM, Lorenzo Pieralisi wrote:
+/*
+ * 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
+ * acpi_parse_spcr().
+ */
+bool qdf2400_e44_present;
+EXPORT_SYMBOL(qdf2400_e44_present);
My eyes, this is horrible but it is not introduced by this patch. It
would have been much better if:
drivers/tty/serial/amba-pl011.c
parsed the SPCR table (again) to detect it instead of relying on this
horrible exported flag.
I didn't want to put any ACPI code in amba-pl011.c, so putting it in
spcr.c made the most sense. I agree the global variable is ugly. If
you have a better idea, I'm all ears.
If it's any consolation, this erratum affects only 1.x silicon, which is
technically pre-production (although a lot of people have them). This
work-around will eventually be reverted.
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 46505396869e..9ae98eeada76 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -79,7 +79,12 @@ config ACPI_DEBUGGER_USER
endif
config ACPI_SPCR_TABLE
- bool
+ bool "ACPI Serial Port Console Redirection Support"
+ default y if ARM64
You need to remove the selection in arch/arm64 then. Also, moving away
from a non-visible config may have consequences on ARM64, Graeme and
Mark are more familiar with the SPCR dependencies so please chime in.
I did raise this as a concern in the previous version of the patch. I
also think it should not be a selectable option.
Keeping the "select" does force SPCR to be enabled on ARM64 ACPI
platforms, but if it's an option for x86, it should be an option for ARM.
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