From: Lucas Stach <dev@lynxeye.de> Date: 2021-12-12 19:18:07
Without a OPP table or a downstream TF-A running on the system the DDRC will
fail to probe, as it has no means to scale the DRAM frequency in that case.
This however will block the bus scaling driver to come up and this in turn
prevents other devices that hook into the interconnect from probing.
If the DDRC is disabled, the interconnect driver will simply ignore it. As
most systems don't want to scale the DRAM frequency, disable the node by
default and only enable it on the systems that actually uses this
capability and provides a valid OPP table in the DT.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
arch/arm64/boot/dts/freescale/imx8mq-evk.dts | 1 +
arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi | 1 +
arch/arm64/boot/dts/freescale/imx8mq.dtsi | 1 +
3 files changed, 3 insertions(+)
Hi Lucas,
On Sun, Dec 12, 2021 at 4:16 PM Lucas Stach [off-list ref] wrote:
Without a OPP table or a downstream TF-A running on the system the DDRC will
fail to probe, as it has no means to scale the DRAM frequency in that case.
This however will block the bus scaling driver to come up and this in turn
prevents other devices that hook into the interconnect from probing.
If the DDRC is disabled, the interconnect driver will simply ignore it. As
most systems don't want to scale the DRAM frequency, disable the node by
default and only enable it on the systems that actually uses this
capability and provides a valid OPP table in the DT.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Should we do the same on imx8mm too?
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From: Lucas Stach <dev@lynxeye.de> Date: 2021-12-13 15:07:33
Am Sonntag, dem 12.12.2021 um 16:29 -0300 schrieb Fabio Estevam:
Hi Lucas,
On Sun, Dec 12, 2021 at 4:16 PM Lucas Stach [off-list ref] wrote:
quoted
Without a OPP table or a downstream TF-A running on the system the DDRC will
fail to probe, as it has no means to scale the DRAM frequency in that case.
This however will block the bus scaling driver to come up and this in turn
prevents other devices that hook into the interconnect from probing.
If the DDRC is disabled, the interconnect driver will simply ignore it. As
most systems don't want to scale the DRAM frequency, disable the node by
default and only enable it on the systems that actually uses this
capability and provides a valid OPP table in the DT.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Should we do the same on imx8mm too?
Not sure, with the i.MX8MM there are a lot more systems that are
providing a valid OPP table. Also I don't see the interconnect being
hooked up to devices in the i.MX8MM DT, so a non-function interconnect
driver, will at least not block other devices as is the case with the
i.MX8MQ.
However, there still is the issue that all those systems those depend
on a downstream TF-A running on the system, as upstream TF-A has no
support for scaling the DDR frequency.
Regards,
Lucas
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From: Martin Kepplinger <martink@posteo.de> Date: 2021-12-13 08:33:16
Am Sonntag, dem 12.12.2021 um 20:15 +0100 schrieb Lucas Stach:
Without a OPP table or a downstream TF-A running on the system the
DDRC will
fail to probe, as it has no means to scale the DRAM frequency in that
case.
This however will block the bus scaling driver to come up and this in
turn
prevents other devices that hook into the interconnect from probing.
If the DDRC is disabled, the interconnect driver will simply ignore
it. As
most systems don't want to scale the DRAM frequency, disable the node
by
default and only enable it on the systems that actually uses this
capability and provides a valid OPP table in the DT.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
Acked-by: Martin Kepplinger <redacted>
but I'd like to append a question to NXP who afaik implemented devfreq
depending on "downstream TF-A" for imx8m: How are your plans to add
support to mainline TF-A?
thank you!
martin
Hi,
On Sun, Dec 12, 2021 at 08:15:41PM +0100, Lucas Stach wrote:
quoted hunk
Without a OPP table or a downstream TF-A running on the system the DDRC will
fail to probe, as it has no means to scale the DRAM frequency in that case.
This however will block the bus scaling driver to come up and this in turn
prevents other devices that hook into the interconnect from probing.
If the DDRC is disabled, the interconnect driver will simply ignore it. As
most systems don't want to scale the DRAM frequency, disable the node by
default and only enable it on the systems that actually uses this
capability and provides a valid OPP table in the DT.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
arch/arm64/boot/dts/freescale/imx8mq-evk.dts | 1 +
arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi | 1 +
arch/arm64/boot/dts/freescale/imx8mq.dtsi | 1 +
3 files changed, 3 insertions(+)
On Sun, Dec 12, 2021 at 08:15:41PM +0100, Lucas Stach wrote:
quoted hunk
Without a OPP table or a downstream TF-A running on the system the DDRC will
fail to probe, as it has no means to scale the DRAM frequency in that case.
This however will block the bus scaling driver to come up and this in turn
prevents other devices that hook into the interconnect from probing.
If the DDRC is disabled, the interconnect driver will simply ignore it. As
most systems don't want to scale the DRAM frequency, disable the node by
default and only enable it on the systems that actually uses this
capability and provides a valid OPP table in the DT.
Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
arch/arm64/boot/dts/freescale/imx8mq-evk.dts | 1 +
arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi | 1 +
arch/arm64/boot/dts/freescale/imx8mq.dtsi | 1 +
3 files changed, 3 insertions(+)