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Filename Latest commit message Latest commit date
Thommy Jakobsson 0c30297ddd spi/zynqmp: remove entry that causes a cs glitch
[ Upstream commit 5dd8304981ecffa77bb72b1c57c4be5dfe6cfae9 ]

In the public interface for chipselect, there is always an entry
commented as "Dummy generic FIFO entry" pushed down to the fifo right
after the activate/deactivate command. The dummy entry is 0x0,
irregardless if the intention was to activate or deactive the cs. This
causes the cs line to glitch rather than beeing activated in the case
when there was an activate command.

This has been observed on oscilloscope, and have caused problems for at
least one specific flash device type connected to the qspi port. After
the change the glitch is gone and cs goes active when intended.

The reason why this worked before (except for the glitch) was because
when sending the actual data, the CS bits are once again set. Since
most flashes uses mode 0, there is always a half clk period anyway for
cs to clk active setup time. If someone would rely on timing from a
chip_select call to a transfer_one, it would fail though.

It is unknown why the dummy entry was there in the first place, git log
seems to be of no help in this case. The reference manual gives no
indication of the necessity of this. In fact the lower 8 bits are a
setup (or hold in case of deactivate) time expressed in cycles. So this
should not be needed to fulfill any setup/hold timings.

Signed-off-by: Thommy Jakobsson <thommyj@gmail.com>
Reviewed-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Link: https://lore.kernel.org/r/20200224162643.29102-1-thommyj@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-25 08:25:45 +01:00
arch ARM: dts: dra7: Add "dma-ranges" property to PCIe RC DT nodes 2020-03-25 08:25:44 +01:00
block blk-mq: insert flush request to the front of dispatch queue 2020-03-21 08:11:57 +01:00
certs
crypto crypto: rename sm3-256 to sm3 in hash_algo_name 2020-02-28 17:22:26 +01:00
Documentation ACPI: watchdog: Allow disabling WDAT at boot 2020-03-21 08:11:47 +01:00
drivers spi/zynqmp: remove entry that causes a cs glitch 2020-03-25 08:25:45 +01:00
fs cifs: add missing mount option to /proc/mounts 2020-03-25 08:25:43 +01:00
include driver code: clarify and fix platform device DMA mask allocation 2020-03-18 07:17:56 +01:00
init kbuild: remove header compile test 2020-03-05 16:43:47 +01:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-28 17:22:20 +01:00
kernel signal: avoid double atomic counter increments for user accounting 2020-03-21 08:11:53 +01:00
lib kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
LICENSES
mm mm: slub: add missing TID bump in kmem_cache_alloc_bulk() 2020-03-21 08:11:58 +01:00
net ipv4: ensure rcu_read_lock() in cipso_v4_error() 2020-03-21 08:11:59 +01:00
samples
scripts kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
security efi: Only print errors about failing to get certs if EFI vars are found 2020-03-12 13:00:14 +01:00
sound ALSA: hda/realtek - Fixed one of HP ALC671 platform Headset Mic supported 2020-03-18 07:17:38 +01:00
tools selftests/rseq: Fix out-of-tree compilation 2020-03-21 08:11:49 +01:00
usr kbuild: fix 'No such file or directory' warning when cleaning 2020-03-12 13:00:09 +01:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:43:48 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
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COPYING
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Makefile Linux 5.4.27 2020-03-21 08:12:00 +01:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.