From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter De Schrijver Subject: Re: [PATCH 2/8] clk: tegra: host1x has fractional divider Date: Mon, 23 Jul 2018 11:50:10 +0300 Message-ID: <20180723085010.GK1636@tbergstrom-lnx.Nvidia.com> References: <20180720134532.13148-1-ben.dooks@codethink.co.uk> <20180720134532.13148-3-ben.dooks@codethink.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <20180720134532.13148-3-ben.dooks@codethink.co.uk> Sender: linux-kernel-owner@vger.kernel.org To: Ben Dooks Cc: linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, pgaikwad@nvidia.com, jonathanh@nvidia.co, thierry.reding@gmail.com, linux-kernel@lists.codethink.co.uk List-Id: linux-tegra@vger.kernel.org On Fri, Jul 20, 2018 at 02:45:26PM +0100, Ben Dooks wrote: > The host1x clock according to both tegra2 and tegra3 manuals is > an 8bit divider with lsb being fractional. This is running into > an issue where the host1x is being set on a tegra20a system to > 266.4MHz but ends up at 222MHz instead. > The fact the hw has a fractional divider, does not mean we're allowed to use it. Due to the non 50% duty cycle of fractional divided clocks, they are not allowed for certain peripherals. Do you have information indicating this is ok for the host1x clock? Peter. > Signed-off-by: Ben Dooks > --- > drivers/clk/tegra/clk-tegra-periph.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/clk/tegra/clk-tegra-periph.c b/drivers/clk/tegra/clk-tegra-periph.c > index 2acba2986bc6..8fa1cecf18a0 100644 > --- a/drivers/clk/tegra/clk-tegra-periph.c > +++ b/drivers/clk/tegra/clk-tegra-periph.c > @@ -644,7 +644,7 @@ static struct tegra_periph_init_data periph_clks[] = { > INT("vde", mux_pllp_pllc_pllm_clkm, CLK_SOURCE_VDE, 61, 0, tegra_clk_vde), > INT("vi", mux_pllm_pllc_pllp_plla, CLK_SOURCE_VI, 20, 0, tegra_clk_vi), > INT("epp", mux_pllm_pllc_pllp_plla, CLK_SOURCE_EPP, 19, 0, tegra_clk_epp), > - INT("host1x", mux_pllm_pllc_pllp_plla, CLK_SOURCE_HOST1X, 28, 0, tegra_clk_host1x), > + MUX("host1x", mux_pllm_pllc_pllp_plla, CLK_SOURCE_HOST1X, 28, 0, tegra_clk_host1x), > INT("mpe", mux_pllm_pllc_pllp_plla, CLK_SOURCE_MPE, 60, 0, tegra_clk_mpe), > INT("2d", mux_pllm_pllc_pllp_plla, CLK_SOURCE_2D, 21, 0, tegra_clk_gr2d), > INT("3d", mux_pllm_pllc_pllp_plla, CLK_SOURCE_3D, 24, 0, tegra_clk_gr3d), > -- > 2.18.0 >