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Filename Latest commit message Latest commit date
Francesco Dolcini ded067f24b PCI: imx6: Fix PERST# start-up sequence
[ Upstream commit a6809941c1f17f455db2cf4ca19c6d8c8746ec25 ]

According to the PCIe standard the PERST# signal (reset-gpio in
fsl,imx* compatible dts) should be kept asserted for at least 100 usec
before the PCIe refclock is stable, should be kept asserted for at
least 100 msec after the power rails are stable and the host should wait
at least 100 msec after it is de-asserted before accessing the
configuration space of any attached device.

From PCIe CEM r2.0, sec 2.6.2

  T-PVPERL: Power stable to PERST# inactive - 100 msec
  T-PERST-CLK: REFCLK stable before PERST# inactive - 100 usec.

From PCIe r5.0, sec 6.6.1

  With a Downstream Port that does not support Link speeds greater than
  5.0 GT/s, software must wait a minimum of 100 ms before sending a
  Configuration Request to the device immediately below that Port.

Failure to do so could prevent PCIe devices to be working correctly,
and this was experienced with real devices.

Move reset assert to imx6_pcie_assert_core_reset(), this way we ensure
that PERST# is asserted before enabling any clock, move de-assert to the
end of imx6_pcie_deassert_core_reset() after the clock is enabled and
deemed stable and add a new delay of 100 msec just afterward.

Link: https://lore.kernel.org/all/20220211152550.286821-1-francesco.dolcini@toradex.com
Link: https://lore.kernel.org/r/20220404081509.94356-1-francesco.dolcini@toradex.com
Fixes: bb38919ec5 ("PCI: imx6: Add support for i.MX6 PCIe controller")
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Richard Zhu <hongxing.zhu@nxp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-06-14 18:11:41 +02:00
arch powerpc/4xx/cpm: Fix return value of __setup() handler 2022-06-14 18:11:41 +02:00
block
certs
crypto crypto: ecrdsa - Fix incorrect use of vli_cmp 2022-06-06 08:33:50 +02:00
Documentation hwmon: Make chip parameter for with_info API mandatory 2022-06-14 18:11:29 +02:00
drivers PCI: imx6: Fix PERST# start-up sequence 2022-06-14 18:11:41 +02:00
fs proc: fix dentry/inode overinstantiating under /proc/${pid}/net 2022-06-14 18:11:41 +02:00
include scsi: fcoe: Fix Wstringop-overflow warnings in fcoe_wwn_from_mac() 2022-06-14 18:11:40 +02:00
init
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-14 18:11:41 +02:00
kernel sched/fair: Fix cfs_rq_clock_pelt() for throttled cfs_rq 2022-06-14 18:11:33 +02:00
lib assoc_array: Fix BUG_ON during garbage collect 2022-06-06 08:33:50 +02:00
LICENSES
mm zsmalloc: fix races between asynchronous zspage free and page migration 2022-06-06 08:33:50 +02:00
net net/smc: postpone sk_refcnt increment in connect() 2022-06-14 18:11:39 +02:00
samples
scripts scripts/faddr2line: Fix overlapping text section failures 2022-06-14 18:11:37 +02:00
security lockdown: also lock down previous kgdb use 2022-06-06 08:33:48 +02:00
sound ASoC: wm2000: fix missing clk_disable_unprepare() on error in wm2000_anc_transition() 2022-06-14 18:11:38 +02:00
tools perf tools: Add missing headers needed by util/data.h 2022-06-14 18:11:34 +02:00
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Makefile Linux 5.4.197 2022-06-06 08:33:51 +02:00
README

Linux kernel
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There are various text files in the Documentation/ subdirectory,
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