Hi Michal,
AFAIK, TF-A does not publish guidelines for clocks/resets for shared IP. It is left to the platforms.
For Tegra platforms, the clocks/reset are managed by a central entity. TF-A is expected to co-ordinate with this entity. Unfortunately, PL011 does not fall in this category and is expected to be kept on by the previous bootloader.
-Varun
-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Michal Simek via TF-A Sent: Monday, June 21, 2021 2:24 PM To: tf-a@lists.trustedfirmware.org Subject: [TF-A] PL011 clock handling between TF-A and Linux
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Hi,
recently we have hit the case where Linux has pl011 driver and using it as a console. The same console is also used by TF-A. If you look at implementation details Linux pl011 driver has in pl011_console_write() clk_enable/clk_disable calls. I can't see any clock handling for PL011 in TF-A that's why I guess that TF-A expectation is that clocks are enabled and must be enabled all the time because pl011 is also used as crashed console. That's why I would like to check with you what's the clock expectation in these shared IP cases. Do you have a requirement that firmware should keep refcount of IP users and never disable clock when only one requires it?
Thanks, Michal -- TF-A mailing list TF-A@lists.trustedfirmware.org https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.trus...