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pi: add skip-init flag to disable-bt overlay #3731

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pi: add skip-init flag to disable-bt overlay #3731

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fwjavox
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@fwjavox fwjavox commented Jul 17, 2020

If this flag is not set, u-boot will fail while trying to (re)init the
uart devices when the disable-bt overlay is used.

Signed-off-by: Florian Wickert [email protected]

pi: add skip-init flag to disable-bt overlay
64c298b 
If this flag is not set, u-boot will fail while trying to (re)init the
uart devices when the disable-bt overlay is used.

Signed-off-by: Florian Wickert <[email protected]>
@pelwell
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pelwell commented Jul 17, 2020

I'm not against this PR in principle, but it needs more explanation of how U-boot fails and why this is the right solution. In particular, I have a few questions:

  1. Why is the skip-init flag needed for a disabled UART?
  2. Using dtoverlay=disable-bt on a Bluetooth-equipped Pi should leave the UARTs in the same state as they would be on a non-Bluetooth Pi, so why haven't we been asked to add skip-init before?

@fwjavox
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fwjavox commented Jul 17, 2020

The skip-init Flag is evaluated by u-boot and helps to prevent double initialization of the hardware.

  1. uart0 is the more important part because uart0 is enabled by default. But the line dtparam=uart1=on in config.txt is enough to trigger the same problem for uart1.
  2. This bug only applies to RPi4 because u-boot treats it very differently. There is no u-boot specific device-tree for the RPi4 anymore (while RPi<=3 do have them), so it reads the already existing device-tree from memory. Before this, u-boot did not care about config.txt and the overlays at all.

@pelwell
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pelwell commented Jul 17, 2020

Is there any situation where you would want U-boot to initialise either of the UARTs? If not, it would be cleaner to patch the Pi 4 dtb.

@fwjavox
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fwjavox commented Jul 17, 2020

For the older RPIs a similar fix was applied to the u-boot internal device-tree: https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

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fwjavox commented Jul 17, 2020

Is there any situation where you would want U-boot to initialise either of the UARTs? If not, it would be cleaner to patch the Pi 4 dtb.

Good question, I cannot think of any reason.

pelwell added a commit to pelwell/linux that referenced this pull request Jul 17, 2020
@pelwell
ARM: dts: Add UART skip-init properties for U-boot
d849c78 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: raspberrypi#3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
@pelwell pelwell mentioned this pull request Jul 17, 2020
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pelwell commented Jul 17, 2020

See #3733 - it would be great if you could test it to confirm it has the desired effect.

pelwell added a commit that referenced this pull request Jul 28, 2020
@pelwell
ARM: dts: Add UART skip-init properties for U-boot
7bbf6b4 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
@pelwell
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pelwell commented Jul 28, 2020

#3733 is now merged.

@fwjavox fwjavox closed this Jul 28, 2020
popcornmix added a commit to raspberrypi/firmware that referenced this pull request Jul 29, 2020
@popcornmix
linux: drm/vc4: Remove UIF from the list of modifiers returned by for…
ee99ec6 
…mat_mod_supported

See: raspberrypi/linux#3665

kernel: ARM: dts: Add UART skip-init properties for U-boot
See: raspberrypi/linux#3731
See: https://lists.denx.de/pipermail/u-boot/2017-April/285606.html
popcornmix added a commit to Hexxeh/rpi-firmware that referenced this pull request Jul 29, 2020
@popcornmix
linux: drm/vc4: Remove UIF from the list of modifiers returned by for…
ffc3ed0 
…mat_mod_supported

See: raspberrypi/linux#3665

kernel: ARM: dts: Add UART skip-init properties for U-boot
See: raspberrypi/linux#3731
See: https://lists.denx.de/pipermail/u-boot/2017-April/285606.html
pelwell added a commit that referenced this pull request Aug 12, 2020
@pelwell
ARM: dts: Add UART skip-init properties for U-boot
ed7a23c 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Aug 12, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
f18388e 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
pelwell added a commit that referenced this pull request Aug 18, 2020
@pelwell
ARM: dts: Add UART skip-init properties for U-boot
8a91365 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Aug 19, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
2b03ab4 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Aug 19, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
d9c2144 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Sep 1, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
eb6e80b 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Sep 1, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
e6f9a41 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Sep 11, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
b16ed12 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
paul-1 pushed a commit to piCorePlayer/linux that referenced this pull request Sep 13, 2020
@pelwell @paul-1
ARM: dts: Add UART skip-init properties for U-boot
14ccc07 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: raspberrypi#3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Sep 15, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
60c695d 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Sep 28, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
5881846 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Oct 2, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
c59592d 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Oct 7, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
1a4d923 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Oct 16, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
1d90d35 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Oct 19, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
d2f31dd 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
popcornmix pushed a commit that referenced this pull request Nov 4, 2020
@pelwell @popcornmix
ARM: dts: Add UART skip-init properties for U-boot
9d46dbd 
U-boot can get stuck trying to initialise UARTs that aren't mapped
to the pin header. There is no reason for U-boot not to rely on the
initialisation by the firmware, so tag both UARTs with the u-boot
magic boolean property "skip-init".

See: #3731
     https://lists.denx.de/pipermail/u-boot/2017-April/285606.html

Signed-off-by: Phil Elwell <[email protected]>
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@fwjavox @pelwell