[PATCH 5.17 054/158] Revert "can: m_can: pci: use custom bit timings for Elkhart Lake"

Greg Kroah-Hartman
2022-05-23T17:54:56Z

From: Jarkko Nikula <jarkko.nikula@linux.intel.com>

commit 14ea4a470494528c7e88da5c4116c24eb027059f upstream.

This reverts commit 0e8ffdf3b86dfd44b651f91b12fcae76c25c453b.

Commit 0e8ffdf3b86d ("can: m_can: pci: use custom bit timings for
Elkhart Lake") broke the test case using bitrate switching.

| ip link set can0 up type can bitrate 500000 dbitrate 4000000 fd on
| ip link set can1 up type can bitrate 500000 dbitrate 4000000 fd on
| candump can0 &
| cangen can1 -I 0x800 -L 64 -e -fb \
| -D 11223344deadbeef55667788feedf00daabbccdd44332211 -n 1 -v -v

Above commit does everything correctly according to the datasheet.
However datasheet wasn't correct.

I got confirmation from hardware engineers that the actual CAN
hardware on Intel Elkhart Lake is based on M_CAN version v3.2.0.
Datasheet was mirroring values from an another specification which was
based on earlier M_CAN version leading to wrong bit timings.

Therefore revert the commit and switch back to common bit timings.

Fixes: ea4c1787685d ("can: m_can: pci: use custom bit timings for Elkhart Lake")
Link: https://lore.kernel.org/all/20220512124144.536850-1-jarkko.nikula@linux.intel.com
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reported-by: Chee Hou Ong <chee.houx.ong@intel.com>
Reported-by: Aman Kumar <aman.kumar@intel.com>
Reported-by: Pallavi Kumari <kumari.pallavi@intel.com>
Cc: <stable@vger.kernel.org> # v5.16+
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/can/m_can/m_can_pci.c | 48 +++-----------------------------------
1 file changed, 4 insertions(+), 44 deletions(-)

--- a/drivers/net/can/m_can/m_can_pci.c
+++ b/drivers/net/can/m_can/m_can_pci.c
@@ -18,14 +18,9 @@

#define M_CAN_PCI_MMIO_BAR 0

+#define M_CAN_CLOCK_FREQ_EHL 200000000
#define CTL_CSR_INT_CTL_OFFSET 0x508

-struct m_can_pci_config {
- const struct can_bittiming_const *bit_timing;
- const struct can_bittiming_const *data_timing;
- unsigned int clock_freq;
-};
-
struct m_can_pci_priv {
struct m_can_classdev cdev;

@@ -89,40 +84,9 @@ static struct m_can_ops m_can_pci_ops =
.read_fifo = iomap_read_fifo,
};

-static const struct can_bittiming_const m_can_bittiming_const_ehl = {
- .name = KBUILD_MODNAME,
- .tseg1_min = 2, /* Time segment 1 = prop_seg + phase_seg1 */
- .tseg1_max = 64,
- .tseg2_min = 1, /* Time segment 2 = phase_seg2 */
- .tseg2_max = 128,
- .sjw_max = 128,
- .brp_min = 1,
- .brp_max = 512,
- .brp_inc = 1,
-};
-
-static const struct can_bittiming_const m_can_data_bittiming_const_ehl = {
- .name = KBUILD_MODNAME,
- .tseg1_min = 2, /* Time segment 1 = prop_seg + phase_seg1 */
- .tseg1_max = 16,
- .tseg2_min = 1, /* Time segment 2 = phase_seg2 */
- .tseg2_max = 8,
- .sjw_max = 4,
- .brp_min = 1,
- .brp_max = 32,
- .brp_inc = 1,
-};
-
-static const struct m_can_pci_config m_can_pci_ehl = {
- .bit_timing = &m_can_bittiming_const_ehl,
- .data_timing = &m_can_data_bittiming_const_ehl,
- .clock_freq = 200000000,
-};
-
static int m_can_pci_probe(struct pci_dev *pci, const struct pci_device_id *id)
{
struct device *dev = &pci->dev;
- const struct m_can_pci_config *cfg;
struct m_can_classdev *mcan_class;
struct m_can_pci_priv *priv;
void __iomem *base;
@@ -150,8 +114,6 @@ static int m_can_pci_probe(struct pci_de
if (!mcan_class)
return -ENOMEM;

- cfg = (const struct m_can_pci_config *)id->driver_data;
-
priv = cdev_to_priv(mcan_class);

priv->base = base;
@@ -163,9 +125,7 @@ static int m_can_pci_probe(struct pci_de
mcan_class->dev = &pci->dev;
mcan_class->net->irq = pci_irq_vector(pci, 0);
mcan_class->pm_clock_support = 1;
- mcan_class->bit_timing = cfg->bit_timing;
- mcan_class->data_timing = cfg->data_timing;
- mcan_class->can.clock.freq = cfg->clock_freq;
+ mcan_class->can.clock.freq = id->driver_data;
mcan_class->ops = &m_can_pci_ops;

pci_set_drvdata(pci, mcan_class);
@@ -218,8 +178,8 @@ static SIMPLE_DEV_PM_OPS(m_can_pci_pm_op
m_can_pci_suspend, m_can_pci_resume);

static const struct pci_device_id m_can_pci_id_table[] = {
- { PCI_VDEVICE(INTEL, 0x4bc1), (kernel_ulong_t)&m_can_pci_ehl, },
- { PCI_VDEVICE(INTEL, 0x4bc2), (kernel_ulong_t)&m_can_pci_ehl, },
+ { PCI_VDEVICE(INTEL, 0x4bc1), M_CAN_CLOCK_FREQ_EHL, },
+ { PCI_VDEVICE(INTEL, 0x4bc2), M_CAN_CLOCK_FREQ_EHL, },
{ } /* Terminating Entry */
};
MODULE_DEVICE_TABLE(pci, m_can_pci_id_table);