From patchwork Mon Jan 11 11:23:59 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philipp Zabel X-Patchwork-Id: 8002571 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id D6B5A9F1C0 for ; Mon, 11 Jan 2016 11:26:37 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9B414202B8 for ; Mon, 11 Jan 2016 11:26:36 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4C1EF20172 for ; Mon, 11 Jan 2016 11:26:35 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1aIab1-0004KG-6s; Mon, 11 Jan 2016 11:25:11 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aIaaW-0003wA-2C for linux-arm-kernel@lists.infradead.org; Mon, 11 Jan 2016 11:24:42 +0000 Received: from paszta.hi.4.pengutronix.de ([10.1.0.120] helo=paszta.pengutronix.de.) by metis.ext.pengutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1aIaa8-0008IC-BP; Mon, 11 Jan 2016 12:24:16 +0100 From: Philipp Zabel To: Shawn Guo Subject: [PATCH v2 3/3] ARM: imx6: Fix procedure to switch the parent of LDB_DI_CLK Date: Mon, 11 Jan 2016 12:23:59 +0100 Message-Id: <1452511439-10472-4-git-send-email-p.zabel@pengutronix.de> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1452511439-10472-1-git-send-email-p.zabel@pengutronix.de> References: <1452511439-10472-1-git-send-email-p.zabel@pengutronix.de> X-SA-Exim-Connect-IP: 10.1.0.120 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160111_032440_391724_4E14015F X-CRM114-Status: GOOD ( 23.63 ) X-Spam-Score: -1.9 (-) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fabio Estevam , Ranjani Vaidyanathan , Dirk Behme , Philipp Zabel , kernel@pengutronix.de, Sean Cross , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Fabio Estevam Due to incorrect placement of the clock gate cell in the ldb_di[x]_clk tree, the glitchy parent mux of ldb_di[x]_clk can cause a glitch to enter the ldb_di_ipu_div divider. If the divider gets locked up, no ldb_di[x]_clk is generated, and the LVDS display will hang when the ipu_di_clk is sourced from ldb_di_clk. To fix the problem, both the new and current parent of the ldb_di_clk should be disabled before the switch. This patch ensures that correct steps are followed when ldb_di_clk parent is switched in the beginning of boot. The glitchy muxes are then registered as read-only. The clock parent can be selected using the assigned-clocks and assigned-clock-parents properties of the ccm device tree node: &clks { assigned-clocks = <&clks IMX6QDL_CLK_LDB_DI0_SEL>, <&clks IMX6QDL_CLK_LDB_DI1_SEL>; assigned-clock-parents = <&clks IMX6QDL_CLK_MMDC_CH1_AXI>, <&clks IMX6QDL_CLK_PLL5_VIDEO_DIV>; }; Signed-off-by: Ranjani Vaidyanathan Signed-off-by: Fabio Estevam Signed-off-by: Philipp Zabel --- Changes since v1: - Rebased onto v4.4 - Allow changing ldb_di_sel via workaround on i.MX6Q revision 1.0, but disable the PLL5_VIDEO_DIV parent. --- drivers/clk/imx/clk-imx6q.c | 202 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 202 insertions(+) diff --git a/drivers/clk/imx/clk-imx6q.c b/drivers/clk/imx/clk-imx6q.c index b4b2541..b4fad26 100644 --- a/drivers/clk/imx/clk-imx6q.c +++ b/drivers/clk/imx/clk-imx6q.c @@ -137,9 +137,83 @@ static struct clk ** const uart_clks[] __initconst = { NULL }; +static int ldb_di_sel_by_clock_id(int clock_id) +{ + switch (clock_id) { + case IMX6QDL_CLK_PLL5_VIDEO_DIV: + if (clk_on_imx6q() && + imx_get_soc_revision() == IMX_CHIP_REVISION_1_0) + return -ENOENT; + return 0; + case IMX6QDL_CLK_PLL2_PFD0_352M: + return 1; + case IMX6QDL_CLK_PLL2_PFD2_396M: + return 2; + case IMX6QDL_CLK_MMDC_CH1_AXI: + return 3; + case IMX6QDL_CLK_PLL3_USB_OTG: + return 4; + default: + return -ENOENT; + } +} + +static void of_assigned_ldb_sels(struct device_node *node, + int *ldb_di0_sel, int *ldb_di1_sel) +{ + struct of_phandle_args clkspec; + int index, rc, num_parents; + int parent, child, sel; + + num_parents = of_count_phandle_with_args(node, "assigned-clock-parents", + "#clock-cells"); + for (index = 0; index < num_parents; index++) { + rc = of_parse_phandle_with_args(node, "assigned-clock-parents", + "#clock-cells", index, &clkspec); + if (rc < 0) { + /* skip empty (null) phandles */ + if (rc == -ENOENT) + continue; + else + return; + } + if (clkspec.np != node || clkspec.args[0] >= IMX6QDL_CLK_END) { + pr_err("ccm: parent clock %d not in ccm\n", index); + return; + } + parent = clkspec.args[0]; + + rc = of_parse_phandle_with_args(node, "assigned-clocks", + "#clock-cells", index, &clkspec); + if (rc < 0) + return; + if (clkspec.np != node || clkspec.args[0] >= IMX6QDL_CLK_END) { + pr_err("ccm: child clock %d not in ccm\n", index); + return; + } + child = clkspec.args[0]; + + if (child != IMX6QDL_CLK_LDB_DI0_SEL && + child != IMX6QDL_CLK_LDB_DI1_SEL) + continue; + + sel = ldb_di_sel_by_clock_id(parent); + if (sel < 0) + pr_err("ccm: invalid ldb_di parent clock\n"); + + if (child == IMX6QDL_CLK_LDB_DI0_SEL) + *ldb_di0_sel = sel; + if (child == IMX6QDL_CLK_LDB_DI1_SEL) + *ldb_di1_sel = sel; + } +} + #define CCM_CCDR 0x04 +#define CCM_CCSR 0x0c +#define CCM_CS2CDR 0x2c #define CCDR_MMDC_CH1_MASK BIT(16) +#define CCSR_PLL3_SW_CLK_SEL BIT(0) static void __init imx6q_mmdc_ch1_mask_handshake(void __iomem *ccm_base) { @@ -150,6 +224,124 @@ static void __init imx6q_mmdc_ch1_mask_handshake(void __iomem *ccm_base) writel_relaxed(reg, ccm_base + CCM_CCDR); } +/* + * The only way to disable the MMDC_CH1 clock is to move it to pll3_sw_clk + * via periph2_clk2_sel and then to disable pll3_sw_clk by selecting the + * bypass clock source, since there is no CG bit for mmdc_ch1. + */ +static void mmdc_ch1_disable(void __iomem *ccm_base) +{ + unsigned int reg; + + clk_set_parent(clk[IMX6QDL_CLK_PERIPH2_CLK2_SEL], + clk[IMX6QDL_CLK_PLL3_USB_OTG]); + + /* + * Handshake with mmdc_ch1 module must be masked when changing + * periph2_clk_sel. + */ + clk_set_parent(clk[IMX6QDL_CLK_PERIPH2], clk[IMX6QDL_CLK_PERIPH2_CLK2]); + + /* Disable pll3_sw_clk by selecting the bypass clock source */ + reg = readl_relaxed(ccm_base + CCM_CCSR); + reg |= CCSR_PLL3_SW_CLK_SEL; + writel_relaxed(reg, ccm_base + CCM_CCSR); +} + +static void mmdc_ch1_reenable(void __iomem *ccm_base) +{ + unsigned int reg; + + /* Enable pll3_sw_clk by disabling the bypass */ + reg = readl_relaxed(ccm_base + CCM_CCSR); + reg &= ~CCSR_PLL3_SW_CLK_SEL; + writel_relaxed(reg, ccm_base + CCM_CCSR); + + clk_set_parent(clk[IMX6QDL_CLK_PERIPH2], clk[IMX6QDL_CLK_PERIPH2_PRE]); +} + +/* + * Need to follow a strict procedure when changing the LDB + * clock, else we can introduce a glitch. Things to keep in + * mind: + * 1. The current and new parent clocks must be disabled. + * 2. The default clock for ldb_dio_clk is mmdc_ch1 which has + * no CG bit. + * 3. In the RTL implementation of the LDB_DI_CLK_SEL mux + * the top four options are in one mux and the PLL3 option along + * with another option is in the second mux. There is third mux + * used to decide between the first and second mux. + * The code below switches the parent to the bottom mux first + * and then manipulates the top mux. This ensures that no glitch + * will enter the divider. + */ +static void init_ldb_clks(struct device_node *np, void __iomem *ccm_base) +{ + unsigned int reg; + int ldb_di0_sel[4] = { 0 }; + int ldb_di1_sel[4] = { 0 }; + int i; + + reg = readl_relaxed(ccm_base + CCM_CS2CDR); + ldb_di0_sel[0] = (reg >> 9) & 7; + ldb_di1_sel[0] = (reg >> 12) & 7; + + of_assigned_ldb_sels(np, &ldb_di0_sel[3], &ldb_di1_sel[3]); + + if (ldb_di0_sel[0] == ldb_di0_sel[3] && + ldb_di1_sel[0] == ldb_di1_sel[3]) + return; + + if (ldb_di0_sel[0] != 3 || ldb_di1_sel[0] != 3) + pr_warn("ccm: ldb_di_sel already changed from reset value\n"); + + if (ldb_di0_sel[0] > 3 || ldb_di1_sel[0] > 3 || + ldb_di0_sel[3] > 3 || ldb_di1_sel[3] > 3) { + pr_err("ccm: ldb_di_sel workaround only for top mux\n"); + return; + } + + ldb_di0_sel[1] = ldb_di0_sel[0] | 4; + ldb_di0_sel[2] = ldb_di0_sel[3] | 4; + ldb_di1_sel[1] = ldb_di1_sel[0] | 4; + ldb_di1_sel[2] = ldb_di1_sel[3] | 4; + + mmdc_ch1_disable(ccm_base); + + for (i = 1; i < 4; i++) { + reg = readl_relaxed(ccm_base + CCM_CS2CDR); + reg &= ~((7 << 9) | (7 << 12)); + reg |= ((ldb_di0_sel[i] << 9) | (ldb_di1_sel[i] << 12)); + writel_relaxed(reg, ccm_base + CCM_CS2CDR); + } + + mmdc_ch1_reenable(ccm_base); +} + +static void disable_anatop_clocks(void __iomem *anatop_base) +{ + unsigned int reg; + + /* Make sure PFDs are disabled at boot. */ + reg = readl_relaxed(anatop_base + 0x100); + /* Cannot gate PFD2 if pll2_pfd2_396m is the parent of MMDC clock */ + if (clk_get_parent(clk[IMX6QDL_CLK_PERIPH_PRE]) == + clk[IMX6QDL_CLK_PLL2_PFD2_396M]) + reg |= 0x00008080; + else + reg |= 0x00808080; + writel_relaxed(reg, anatop_base + 0x100); + + reg = readl_relaxed(anatop_base + 0xf0); + reg |= 0x80808080; + writel_relaxed(reg, anatop_base + 0xf0); + + /* Make sure PLLs is disabled */ + reg = readl_relaxed(anatop_base + 0xa0); + reg &= ~(1 << 13); + writel_relaxed(reg, anatop_base + 0xa0); +} + static void __init imx6q_clocks_init(struct device_node *ccm_node) { struct device_node *np; @@ -287,6 +479,8 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node) clk[IMX6QDL_CLK_PLL5_POST_DIV] = clk_register_divider_table(NULL, "pll5_post_div", "pll5_video", CLK_SET_RATE_PARENT, base + 0xa0, 19, 2, 0, post_div_table, &imx_ccm_lock); clk[IMX6QDL_CLK_PLL5_VIDEO_DIV] = clk_register_divider_table(NULL, "pll5_video_div", "pll5_post_div", CLK_SET_RATE_PARENT, base + 0x170, 30, 2, 0, video_div_table, &imx_ccm_lock); + disable_anatop_clocks(base); + np = ccm_node; base = of_iomap(np, 0); WARN_ON(!base); @@ -313,6 +507,14 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node) clk[IMX6QDL_CLK_GPU3D_SHADER_SEL] = imx_clk_mux("gpu3d_shader_sel", base + 0x18, 8, 2, gpu3d_shader_sels, ARRAY_SIZE(gpu3d_shader_sels)); clk[IMX6QDL_CLK_IPU1_SEL] = imx_clk_mux("ipu1_sel", base + 0x3c, 9, 2, ipu_sels, ARRAY_SIZE(ipu_sels)); clk[IMX6QDL_CLK_IPU2_SEL] = imx_clk_mux("ipu2_sel", base + 0x3c, 14, 2, ipu_sels, ARRAY_SIZE(ipu_sels)); + + /* + * The LDB_DI0/1_SEL muxes are registered read-only due to a hardware + * bug. Set the muxes to the requested values before registering the + * ldb_di_sel clocks. + */ + init_ldb_clks(np, base); + clk[IMX6QDL_CLK_LDB_DI0_SEL] = imx_clk_mux_ldb("ldb_di0_sel", base + 0x2c, 9, 3, ldb_di_sels, ARRAY_SIZE(ldb_di_sels)); clk[IMX6QDL_CLK_LDB_DI1_SEL] = imx_clk_mux_ldb("ldb_di1_sel", base + 0x2c, 12, 3, ldb_di_sels, ARRAY_SIZE(ldb_di_sels)); clk[IMX6QDL_CLK_IPU1_DI0_PRE_SEL] = imx_clk_mux_flags("ipu1_di0_pre_sel", base + 0x34, 6, 3, ipu_di_pre_sels, ARRAY_SIZE(ipu_di_pre_sels), CLK_SET_RATE_PARENT);