On 2026-06-25T17:41:21, Jordi T <[email protected]> wrote: > pinctrl: single: parse gpio-range as a raw array (O(N^2) -> O(N)) > > single_add_gpio_func() calls ofnode_parse_phandle_with_args() once per > gpio-range entry. With a flat device tree, every call re-iterates the > property from index 0 and, because cellname is set, performs an > fdt_node_offset_by_phandle() (a full-FDT scan) at every step. The total > cost is therefore quadratic in the number of entries and proportional to > the size of the device tree. > > The impact depends on when the pinctrl is probed. On the J722S EVM > defconfig, pinctrl@f4000 (main_pmx0, the SoC's stock 7-entry gpio-range) > is probed after relocation (caches on): single_add_gpio_func() takes > ~18 ms there and ~1 ms with this change. When the node is probed before > relocation (caches off) the same parse takes hundreds of ms; on a board > that probes it pre-relocation and runs LPDDR4 clocked down it reached > 723 ms, cut to 22 ms here. Any pinctrl-single user with a populated > gpio-range property pays this cost. > > The phandle target is never dereferenced by this function (only the > argument cells are stored), so resolve it only for the first entry to > learn the per-entry cell count, then read the argument cells directly > with ofnode_read_u32_index() and allocate the ranges in one block. A > zero phandle still terminates the list, as in the original loop. This > follows the existing pinctrl-single,gpio-range usage observed in current > DTs, where entries use the same provider and therefore a uniform > per-entry cell count. > > Signed-off-by: Jordi Trepat Mur <[email protected]> > Reviewed-by: Anshul Dalal <[email protected]> > > drivers/pinctrl/pinctrl-single.c | 79 +++++++++++++++++++++++++++++++--------- > 1 file changed, 62 insertions(+), 17 deletions(-)
Reviewed-by: Simon Glass <[email protected]>
