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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-19 02:34:01 +08:00
linux-next/drivers/bus
Jeffrey Hugo 85a087df4a bus: mhi: core: Remove link_status() callback
If the MHI core detects invalid data due to a PCI read, it calls into
the controller via link_status() to double check that the link is infact
down.  All in all, this is pretty pointless, and racy.  There are no good
reasons for this, and only drawbacks.

Its pointless because chances are, the controller is going to do the same
thing to determine if the link is down - attempt a PCI access and compare
the result.  This does not make the link status decision any smarter.

Its racy because its possible that the link was down at the time of the
MHI core access, but then recovered before the controller access.  In this
case, the controller will indicate the link is not down, and the MHI core
will precede to use a bad value as the MHI core does not attempt to retry
the access.

Retrying the access in the MHI core is a bad idea because again, it is
racy - what if the link is down again?  Furthermore, there may be some
higher level state associated with the link status, that is now invalid
because the link went down.

The only reason why the MHI core could see "invalid" data when doing a PCI
access, that is actually valid, is if the register actually contained the
PCI spec defined sentinel for an invalid access.  In this case, it is
arguable that the MHI implementation broken, and should be fixed, not
worked around.

Therefore, remove the link_status() callback before anyone attempts to
implement it.

Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20200430190555.32741-4-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-05 16:58:35 +02:00
..
fsl-mc bus: fsl-mc: add api to retrieve mc version 2020-03-30 11:50:49 +11:00
mhi bus: mhi: core: Remove link_status() callback 2020-05-05 16:58:35 +02:00
arm-cci.c bus: arm-cci: remove unnecessary unreachable() 2018-05-14 01:22:49 -07:00
brcmstb_gisb.c This pull request contains Broadcom ARM/ARM64/MIPS SoCs drivers changes 2019-06-17 04:52:52 -07:00
da8xx-mstpri.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
hisi_lpc.c bus: hisi_lpc: Fixup IO ports addresses to avoid use-after-free in host removal 2020-02-28 17:30:49 +08:00
imx-weim.c bus: imx-weim: remove incorrect __init annotations 2019-09-04 17:59:32 +02:00
Kconfig bus: mhi: core: Add support for registering MHI controllers 2020-03-19 07:41:04 +01:00
Makefile bus: mhi: core: Add support for registering MHI controllers 2020-03-19 07:41:04 +01:00
mips_cdmm.c MIPS/BUS/CDMM: Convert to hotplug state machine 2016-09-06 18:30:25 +02:00
moxtet.c bus: moxtet: fix potential stack buffer overflow 2020-02-15 10:33:19 -08:00
mvebu-mbus.c bus: mvebu-mbus: Convert to using %pOFn instead of device_node.name 2018-09-28 16:41:57 -05:00
omap_l3_noc.c bus: omap: add MODULE_LICENSE tags 2018-01-11 18:02:56 -08:00
omap_l3_noc.h bus: omap_l3_noc: Fix master id address decoding for OMAP5 2015-05-04 10:21:01 -07:00
omap_l3_smx.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
omap_l3_smx.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
omap-ocp2scp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 2019-05-30 11:26:37 -07:00
qcom-ebi2.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
simple-pm-bus.c drivers: bus: Add Simple Power-Managed Bus Driver 2015-02-24 06:36:18 +09:00
sun50i-de2.c bus: add bus driver for accessing Allwinner A64 DE2 2018-06-28 10:20:19 +02:00
sunxi-rsb.c bus: sunxi-rsb: Return correct data when mixing 16-bit and 8-bit reads 2020-02-24 12:02:38 +01:00
tegra-aconnect.c bus: tegra-aconnect: add system sleep callbacks 2019-03-28 17:26:14 +01:00
tegra-gmi.c bus: Add support for Tegra Generic Memory Interface 2016-11-15 17:27:53 +01:00
ti-pwmss.c bus/ti-pwmss: move TI PWMSS driver from PWM to bus subsystem 2019-10-17 21:17:42 +01:00
ti-sysc.c Merge branch 'fix-lcdc-quirk' into omap-for-v5.7/ti-sysc 2020-03-10 09:06:02 -07:00
ts-nbus.c gpiolib: Pass array info to get/set array functions 2018-09-13 11:16:54 +02:00
uniphier-system-bus.c bus: uniphier-system-bus: use devm_platform_ioremap_resource() 2019-09-05 17:57:18 +02:00
vexpress-config.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00