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[PATCH 10/11] hw/gpio/pl061: Document a shortcoming in our implementatio
From: |
Peter Maydell |
Subject: |
[PATCH 10/11] hw/gpio/pl061: Document a shortcoming in our implementation |
Date: |
Fri, 2 Jul 2021 11:40:17 +0100 |
The Luminary PL061s in the Stellaris LM3S9695 don't all have the same
reset value for GPIOPUR. We can get away with not letting the board
configure the PUR reset value because we don't actually wire anything
up to the lines which should reset to pull-up. Add a comment noting
this omission.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
Not worth actually fixing, but I wanted a note since I spotted this
while I was reading the datasheet anyway.
---
hw/gpio/pl061.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/hw/gpio/pl061.c b/hw/gpio/pl061.c
index 8d12b2d6b97..2cb3a231b43 100644
--- a/hw/gpio/pl061.c
+++ b/hw/gpio/pl061.c
@@ -455,6 +455,15 @@ static void pl061_enter_reset(Object *obj, ResetType type)
trace_pl061_reset(DEVICE(s)->canonical_path);
/* reset values from PL061 TRM, Stellaris LM3S5P31 & LM3S8962 Data Sheet */
+
+ /*
+ * FIXME: For the LM3S6965, not all of the PL061 instances have the
+ * same reset values for GPIOPUR, GPIOAFSEL and GPIODEN, so in theory
+ * we should allow the board to configure these via properties.
+ * In practice, we don't wire anything up to the affected GPIO lines
+ * (PB7, PC0, PC1, PC2, PC3 -- they're used for JTAG), so we can
+ * get away with this inaccuracy.
+ */
s->data = 0;
s->old_in_data = 0;
s->dir = 0;
--
2.20.1
- Re: [PATCH 04/11] hw/gpio/pl061: Add tracepoints for register read and write, (continued)
- [PATCH 08/11] hw/arm/virt: Make PL061 GPIO lines pulled low, not high, Peter Maydell, 2021/07/02
- [PATCH 07/11] hw/gpio/pl061: Make pullup/pulldown of outputs configurable, Peter Maydell, 2021/07/02
- [PATCH 09/11] hw/gpio/pl061: Convert to 3-phase reset and assert GPIO lines correctly on reset, Peter Maydell, 2021/07/02
- [PATCH 11/11] hw/arm/stellaris: Expand comment about handling of OLED chipselect, Peter Maydell, 2021/07/02
- [PATCH 10/11] hw/gpio/pl061: Document a shortcoming in our implementation,
Peter Maydell <=
- [PATCH 05/11] hw/gpio/pl061: Document the interface of this device, Peter Maydell, 2021/07/02
- [PATCH 06/11] hw/gpio/pl061: Honour Luminary PL061 PUR and PDR registers, Peter Maydell, 2021/07/02