From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752890AbdIXUAk (ORCPT ); Sun, 24 Sep 2017 16:00:40 -0400 Received: from mail-wm0-f54.google.com ([74.125.82.54]:46578 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752824AbdIXUAh (ORCPT ); Sun, 24 Sep 2017 16:00:37 -0400 X-Google-Smtp-Source: AOwi7QDG97inFWPPWDr1XeoX0IW83WjIEgW8W47SBwVImnjqJwi9gQEJOrT/vjpNoC65PvPrSKsdkg== From: Jerome Brunet To: Stephen Boyd , Michael Turquette Cc: Jerome Brunet , linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, Russell King , Linus Walleij , Quentin Schulz , Kevin Hilman , Peter De Schrijver Subject: [PATCH v4 00/10] clk: implement clock rate protection mechanism Date: Sun, 24 Sep 2017 22:00:20 +0200 Message-Id: <20170924200030.6227-1-jbrunet@baylibre.com> X-Mailer: git-send-email 2.13.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This Patchset is related the RFC [0] and the discussion around CLK_SET_RATE_GATE available here [1] This patchset introduce clock protection to the CCF core. This can then be used for: * Provide a way for a consumer to claim exclusivity over the rate control of a provider. Some clock consumers require that a clock rate must not deviate from its selected frequency. There can be several reasons for this, not least of which is that some hardware may not be able to handle or recover from a glitch caused by changing the clock rate while the hardware is in operation. For such HW, The ability to get exclusive control of a clock's rate, and release that exclusivity, could be seen as a fundamental clock rate control primitive. The exclusivity is not preemptible, so when claimed more than once, is rate is effectively locked. * Provide a similar functionality to providers themselves, fixing CLK_SET_RATE_GATE flag (enforce clock gating along the tree). While there might still be a few platforms relying the broken implementation, tests done has shown this change to be pretty safe. Changes since v3: [3] - Reorder patches following Stephen comments - Add before/after examples to the cosmetic change - Remove loops around protection where possible - Rename the API from "protect" to "exclusive" which decribe what the code better Changes since v2: [2] - Fix issues reported by Adriana Reus (Thanks !) - Dropped patch "clk: move CLK_SET_RATE_GATE protection from prepare to enable". This was broken as the protect count, like the prepare_count should only be accessed under the prepare_lock. Changes since v1: [1] - Check if the rate would actually change before continuing, and bail-out early if not. Changes since RFC: [0] - s/clk_protect/clk_rate_protect - Request rework around core_nolock function - Add clk_set_rate_protect - Reword clk_rate_protect and clk_unprotect documentation - Add few comments to explain the code - Add fixes for CLK_SET_RATE_GATE This was tested with the audio use case mentioned in [1] [0]: https://lkml.kernel.org/r/20170321183330.26722-1-jbrunet@baylibre.com [1]: https://lkml.kernel.org/r/148942423440.82235.17188153691656009029@resonance [2]: https://lkml.kernel.org/r/20170521215958.19743-1-jbrunet@baylibre.com [3]: https://lkml.kernel.org/r/20170612194438.12298-1-jbrunet@baylibre.com Jerome Brunet (10): clk: fix incorrect usage of ENOSYS clk: take the prepare lock out of clk_core_set_parent clk: add clk_core_set_phase_nolock function clk: rework calls to round and determine rate callbacks clk: use round rate to bail out early in set_rate clk: add clock protection mechanism to clk core clk: cosmetic changes to clk_summary debugfs entry clk: fix CLK_SET_RATE_GATE with clock rate protection clk: add clk_rate_exclusive api clk: fix set_rate_range when current rate is out of range drivers/clk/clk.c | 505 +++++++++++++++++++++++++++++++++++++------ include/linux/clk-provider.h | 1 + include/linux/clk.h | 57 +++++ 3 files changed, 492 insertions(+), 71 deletions(-) -- 2.13.5