D47946.id147612.diff
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	diff --git a/sys/dev/uart/uart_dev_pl011.c b/sys/dev/uart/uart_dev_pl011.c
	--- a/sys/dev/uart/uart_dev_pl011.c
	+++ b/sys/dev/uart/uart_dev_pl011.c
	@@ -172,6 +172,27 @@
	uart_pl011_probe(struct uart_bas *bas)
	{

	+ /*
	+ * Versions of QEMU before 41f7b58b634e (8.3) reproted bogus values for
	+ * this tabe. The PL011 IP is always 32-bits wide and should be shifted
	+ * 2 to match the 4-byte size of the data. QEMu reported these values
	+ * incorrectly before that.
	+ * https://github.com/qemu/qemu/commit/41f7b58b634ec3b60ae874375d2bbb61d790971e
	+ *
	+ * In additon, other hardware vendors also reported this value
	+ * incorrectly. It's not tied to what the ACPI device node is, but was a
	+ * misunderstanding coupled with a Linux driver that didn't need the
	+ * right values. Quriks used to be used to ignore the bad values, now we
	+ * detect the historic mistake and override (to allow for a future where
	+ * we may need to override these values).
	+ *
	+ * PL011 Docs: https://developer.arm.com/documentation/ddi0183/latest/
	+ */
	+ if (bas->regshift == 0 \|\| bas->regiowidth == 1) {
	+ bas->regshift = 2;
	+ bas->regiowidth = 4;
	+ }
	+
	return (0);
	}