linux-kernel - Re: [Patch v2 1/2] firmware: tegra: add suspend hook and reset BPMP IPC early on resume

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Message-ID: <ZSfSACoBr1rDF4Gk@orome.fritz.box>
Date:   Thu, 12 Oct 2023 13:01:20 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Sumit Gupta <sumitg@...dia.com>
Cc:     treding@...dia.com, jonathanh@...dia.com,
        krzysztof.kozlowski@...aro.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org, bbasu@...dia.com
Subject: Re: [Patch v2 1/2] firmware: tegra: add suspend hook and reset BPMP
 IPC early on resume

On Mon, Oct 09, 2023 at 03:35:56PM +0530, Sumit Gupta wrote:
> Add suspend hook and a 'suspended' field in the 'struct tegra_bpmp'
> to mark if BPMP is suspended. Also, add a 'flags' field in the
> 'struct tegra_bpmp_message' whose 'TEGRA_BPMP_MESSAGE_RESET' bit
> can be set from the Tegra MC driver to signal that the reset of BPMP
> IPC channels is required before sending MRQ to the BPMP FW.
> Together both the fields allow us to handle any requests that might
> be sent too soon as they can cause hang during system resume.
> One case where we see BPMP requests being sent before the BPMP driver
> has resumed is the memory bandwidth requests which are triggered by
> onlining the CPUs during system resume. The CPUs are onlined before
> the BPMP has resumed and we need to reset the BPMP IPC channels to
> handle these requests.
> The additional check for 'flags' is done to avoid any un-intended BPMP
> IPC reset if the tegra_bpmp_transfer*() API gets called during suspend
> sequence after the BPMP driver is suspended.
> 
> Fixes: f41e1442ac5b ("cpufreq: tegra194: add OPP support and set bandwidth")
> Co-developed-by: Thierry Reding <treding@...dia.com>
> Signed-off-by: Thierry Reding <treding@...dia.com>
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---
>  drivers/firmware/tegra/bpmp.c | 30 ++++++++++++++++++++++++++++++
>  include/soc/tegra/bpmp.h      |  6 ++++++
>  2 files changed, 36 insertions(+)

Krzysztof,

if you want to pick these up instead of me taking them through the Tegra
tree:

Acked-by: Thierry Reding <treding@...dia.com>

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