From mboxrd@z Thu Jan 1 00:00:00 1970 From: "elaine.zhang" Subject: Re: [PATCH v1] clk: Export __clk_lookup() Date: Thu, 23 Jul 2020 09:49:35 +0800 Message-ID: <99eebfa5-e775-37a8-6c76-90ae2444b253@rock-chips.com> References: <20200722023230.10826-1-zhangqing@rock-chips.com> <14639646.VOZsFJ8Tpa@phil> <159546549321.3847286.4678382117195983280@swboyd.mtv.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-clk-owner@vger.kernel.org To: Stephen Boyd , Heiko Stuebner Cc: mturquette@baylibre.com, linux-clk@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org, xxx@rock-chips.com, xf@rock-chips.com, huangtao@rock-chips.com, kever.yang@rock-chips.com List-Id: linux-rockchip.vger.kernel.org 在 2020/7/23 上午9:42, elaine.zhang 写道: > > 在 2020/7/23 上午8:51, Stephen Boyd 写道: >> Quoting Heiko Stuebner (2020-07-22 11:26:50) >>> Hi Elaine, >>> >>> Am Mittwoch, 22. Juli 2020, 04:32:30 CEST schrieb Elaine Zhang: >>>> Export __clk_lookup() to support user built as module. >>>> >>>> ERROR: >>>> drivers/clk/rockchip/clk.ko: In function >>>> `rockchip_clk_protect_critical': >>>> drivers/clk/rockchip/clk.c:741: >>>> undefined reference to `__clk_lookup' >>> can you elaborate a bit more on why this would be needed? >>> >>> Because right now the Rockchip clocks are of course built into >>> the main kernel image (especially due to them being needed during early >>> boot) and __clk_lookup actually is a pretty deep part of the clock- >>> framework itself, as probably also denoted by the "__" in the function >>> name. >>> >> Can you stop using __clk_lookup()? The plan is to remove it. > > Rk use  __clk_lookup() as: > > drivers/clk/rockchip/clk.c > > void __init rockchip_clk_protect_critical(const char *const clocks[], >                                           int nclocks) > { >         int i; > >         /* Protect the clocks that needs to stay on */ >         for (i = 0; i < nclocks; i++) { >                 struct clk *clk = __clk_lookup(clocks[i]); > >                 if (clk) >                         clk_prepare_enable(clk); >         } > } > e.g: > > drivers/clk/rockchip/clk-rk3328.c > > static const char *const rk3328_critical_clocks[] __initconst = { >         "aclk_bus", >         "aclk_bus_niu", >         "pclk_bus", >         "pclk_bus_niu", >         "hclk_bus", >         "hclk_bus_niu", >         "aclk_peri", > ............ > > }; > > If have plan to remove the __clk_lookup, I need to replace the > rockchip_clk_protect_critical, and use the flag CLK_IS_CRITICAL.(but > use flag CLK_IS_CRITICAL, the enable count is always "0") Use the CLK_IS_CRITICAL, there is no guarantee that the parent clk is enabled, So the flag CLK_IS_CRITICAL need to be added to all special clks according to the clk tree. > >> >>