On Wed, Dec 13, 2017 at 03:11:33PM -0600, Timur Tabi wrote:

On 12/13/2017 06:45 AM, Lorenzo Pieralisi wrote:

quoted

quoted

+/*
+ * 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.

I told you my idea. It could have been made easier by reusing the
ACPI_DECLARE_PROBE_ENTRY() mechanism.

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.

The sooner the better.

Lorenzo