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From: Peter Maydell <peter.maydell@linaro.org>
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Subject: [Qemu-devel] [PULL 01/13] fsl-imx6: Swap Ethernet interrupt defines
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From: Guenter Roeck <linux@roeck-us.net>
The sabrelite machine model used by qemu-system-arm is based on the
Freescale/NXP i.MX6Q processor. This SoC has an on-board ethernet
controller which is supported in QEMU using the imx_fec.c module
(actually called imx.enet for this model.)
The include/hw/arm/fsm-imx6.h file defines the interrupt vectors for the
imx.enet device like this:
#define FSL_IMX6_ENET_MAC_1588_IRQ 118
#define FSL_IMX6_ENET_MAC_IRQ 119
According to https://www.nxp.com/docs/en/reference-manual/IMX6DQRM.pdf,
page 225, in Table 3-1. ARM Cortex A9 domain interrupt summary,
interrupts are as follows.
150 ENET MAC 0 IRQ
151 ENET MAC 0 1588 Timer interrupt
where
150 - 32 =3D=3D 118
151 - 32 =3D=3D 119
In other words, the vector definitions in the fsl-imx6.h file are reversed.
Fixing the interrupts alone causes problems with older Linux kernels:
The Ethernet interface will fail to probe with Linux v4.9 and earlier.
Linux v4.1 and earlier will crash due to a bug in Ethernet driver probe
error handling. This is a Linux kernel problem, not a qemu problem:
the Linux kernel only worked by accident since it requested both interrupts.
For backward compatibility, generate the Ethernet interrupt on both interru=
pt
lines. This was shown to work from all Linux kernel releases starting with
v3.16.
Link: https://bugs.launchpad.net/qemu/+bug/1753309
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Message-id: 1520723090-22130-1-git-send-email-linux@roeck-us.net
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
include/hw/arm/fsl-imx6.h | 4 ++--
hw/net/imx_fec.c | 28 +++++++++++++++++++++++++++-
2 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/include/hw/arm/fsl-imx6.h b/include/hw/arm/fsl-imx6.h
index ec6c509d74..06f8aaeda4 100644
--- a/include/hw/arm/fsl-imx6.h
+++ b/include/hw/arm/fsl-imx6.h
@@ -438,8 +438,8 @@ typedef struct FslIMX6State {
#define FSL_IMX6_HDMI_MASTER_IRQ 115
#define FSL_IMX6_HDMI_CEC_IRQ 116
#define FSL_IMX6_MLB150_LOW_IRQ 117
-#define FSL_IMX6_ENET_MAC_1588_IRQ 118
-#define FSL_IMX6_ENET_MAC_IRQ 119
+#define FSL_IMX6_ENET_MAC_IRQ 118
+#define FSL_IMX6_ENET_MAC_1588_IRQ 119
#define FSL_IMX6_PCIE1_IRQ 120
#define FSL_IMX6_PCIE2_IRQ 121
#define FSL_IMX6_PCIE3_IRQ 122
diff --git a/hw/net/imx_fec.c b/hw/net/imx_fec.c
index 9506f9b69f..6e297c5480 100644
--- a/hw/net/imx_fec.c
+++ b/hw/net/imx_fec.c
@@ -417,7 +417,33 @@ static void imx_enet_write_bd(IMXENETBufDesc *bd, dma_=
addr_t addr)
=20
static void imx_eth_update(IMXFECState *s)
{
- if (s->regs[ENET_EIR] & s->regs[ENET_EIMR] & ENET_INT_TS_TIMER) {
+ /*
+ * Previous versions of qemu had the ENET_INT_MAC and ENET_INT_TS_TIMER
+ * interrupts swapped. This worked with older versions of Linux (4.14
+ * and older) since Linux associated both interrupt lines with Ethernet
+ * MAC interrupts. Specifically,
+ * - Linux 4.15 and later have separate interrupt handlers for the MAC=
and
+ * timer interrupts. Those versions of Linux fail with versions of Q=
EMU
+ * with swapped interrupt assignments.
+ * - In linux 4.14, both interrupt lines were registered with the Ethe=
rnet
+ * MAC interrupt handler. As a result, all versions of qemu happen to
+ * work, though that is accidental.
+ * - In Linux 4.9 and older, the timer interrupt was registered direct=
ly
+ * with the Ethernet MAC interrupt handler. The MAC interrupt was
+ * redirected to a GPIO interrupt to work around erratum ERR006687.
+ * This was implemented using the SOC's IOMUX block. In qemu, this G=
PIO
+ * interrupt never fired since IOMUX is currently not supported in q=
emu.
+ * Linux instead received MAC interrupts on the timer interrupt.
+ * As a result, qemu versions with the swapped interrupt assignment =
work,
+ * albeit accidentally, but qemu versions with the correct interrupt
+ * assignment fail.
+ *
+ * To ensure that all versions of Linux work, generate ENET_INT_MAC
+ * interrrupts on both interrupt lines. This should be changed if and =
when
+ * qemu supports IOMUX.
+ */
+ if (s->regs[ENET_EIR] & s->regs[ENET_EIMR] &
+ (ENET_INT_MAC | ENET_INT_TS_TIMER)) {
qemu_set_irq(s->irq[1], 1);
} else {
qemu_set_irq(s->irq[1], 0);
--=20
2.16.2