Re: [PATCH] interconnect: increase ICC_DYN_ID_START

[Johan Hovold <johan@kernel.org>]

On Wed, Jun 25, 2025 at 03:34:23PM +0200, Gabor Juhos wrote:
> Since commit d30f83d278a9 ("interconnect: core: Add dynamic id allocation
> support"), interconnect node ids greater than or equal to ICC_DYN_ID_START
> are reserved for dynamic id allocation. Yet the icc_node_create_nolock()
> function allows to directly use such ids for creating nodes. This can
> cause problems by executing dynamic id related codepaths even for nodes
> intended to use static ids.
> 
> For example, the 'nsscc-ipq9574' driver creates interconnect nodes with
> static ids starting from 19148. Because these ids belongs to the dynamic
> id range, the icc_node_add() function replaces the node names
> unexpectedly.
> 
> The node names looked like this before the change:
> 
>   # grep nss_cc /sys/kernel/debug/interconnect/interconnect_summary
>   nss_cc_nssnoc_ppe_clk_master                          0            0
>   nss_cc_nssnoc_ppe_clk_slave                           0            0
>   nss_cc_nssnoc_ppe_cfg_clk_master                      0            0
>   ...
> 
> And those have an unexpected suffix now:
> 
>   # grep nss_cc /sys/kernel/debug/interconnect/interconnect_summary
>   nss_cc_nssnoc_ppe_clk_master@39b00000.clock-controller            0            0
>   nss_cc_nssnoc_ppe_clk_slave@39b00000.clock-controller            0            0
>   nss_cc_nssnoc_ppe_cfg_clk_master@39b00000.clock-controller            0            0
>   ...
> 
> Increase the value of ICC_DYN_ID_START to avoid this.
> 
> Also, add sanity check to the icc_node_create_nolock() function to prevent
> directly creating nodes with ids reserved for dynamic allocation in order
> to detect these kind of problems.
> 
> Fixes: d30f83d278a9 ("interconnect: core: Add dynamic id allocation support")
> Signed-off-by: Gabor Juhos <j4g8y7@gmail.com>

Reviewed-by: Johan Hovold <johan+linaro@kernel.org>