From patchwork Sat Sep 26 17:04:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 11803019 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DF6886CB for ; Mon, 28 Sep 2020 07:07:05 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A16162078B for ; Mon, 28 Sep 2020 07:07:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="I6rA9dA4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A16162078B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=crapouillou.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 182326E32A; Mon, 28 Sep 2020 07:06:28 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from crapouillou.net (crapouillou.net [89.234.176.41]) by gabe.freedesktop.org (Postfix) with ESMTPS id CBE426E17B for ; Sat, 26 Sep 2020 17:05:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1601139909; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2X8WxJ+5iLQbOvutkSewBQk7CE1YfeGwzy9VSDqe9S0=; b=I6rA9dA4uzDSVpT5yQzIJx3IZ0W6D6VZ//7M4OSt1Copvb/41AT3ibrAPVQV0dEaJzXP+l AN8G9JV9GoUKJ+cnYo40xBkMtYLSANLE4wQqcIwHwcIU5SqViT/QkRL5N9HvD7tuHutUuQ XGyufmenGVWp7QuansaTMAetGFG+bpk= From: Paul Cercueil To: David Airlie , Daniel Vetter Subject: [PATCH v2 1/7] drm/ingenic: Reset pixclock rate when parent clock rate changes Date: Sat, 26 Sep 2020 19:04:55 +0200 Message-Id: <20200926170501.1109197-2-paul@crapouillou.net> In-Reply-To: <20200926170501.1109197-1-paul@crapouillou.net> References: <20200926170501.1109197-1-paul@crapouillou.net> MIME-Version: 1.0 X-Mailman-Approved-At: Mon, 28 Sep 2020 07:06:24 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Cercueil , od@zcrc.me, Sam Ravnborg , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Old Ingenic SoCs can overclock very well, up to +50% of their nominal clock rate, whithout requiring overvolting or anything like that, just by changing the rate of the main PLL. Unfortunately, all clocks on the system are derived from that PLL, and when the PLL rate is updated, so is our pixel clock. To counter that issue, we make sure that the panel is in VBLANK before the rate change happens, and we will then re-set the pixel clock rate afterwards, once the PLL has been changed, to be as close as possible to the pixel rate requested by the encoder. v2: Add comment about mutex usage Signed-off-by: Paul Cercueil Acked-by: Sam Ravnborg --- drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 61 ++++++++++++++++++++++- 1 file changed, 60 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c index 937d080f5d06..eadfe3a20bf1 100644 --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -71,6 +72,21 @@ struct ingenic_drm { bool panel_is_sharp; bool no_vblank; + + /* + * clk_mutex is used to synchronize the pixel clock rate update with + * the VBLANK. When the pixel clock's parent clock needs to be updated, + * clock_nb's notifier function will lock the mutex, then wait until the + * next VBLANK. At that point, the parent clock's rate can be updated, + * and the mutex is then unlocked. If an atomic commit happens in the + * meantime, it will lock on the mutex, effectively waiting until the + * clock update process finishes. Finally, the pixel clock's rate will + * be recomputed when the mutex has been released, in the pending atomic + * commit, or a future one. + */ + struct mutex clk_mutex; + bool update_clk_rate; + struct notifier_block clock_nb; }; static const u32 ingenic_drm_primary_formats[] = { @@ -119,6 +135,29 @@ static inline struct ingenic_drm *drm_crtc_get_priv(struct drm_crtc *crtc) return container_of(crtc, struct ingenic_drm, crtc); } +static inline struct ingenic_drm *drm_nb_get_priv(struct notifier_block *nb) +{ + return container_of(nb, struct ingenic_drm, clock_nb); +} + +static int ingenic_drm_update_pixclk(struct notifier_block *nb, + unsigned long action, + void *data) +{ + struct ingenic_drm *priv = drm_nb_get_priv(nb); + + switch (action) { + case PRE_RATE_CHANGE: + mutex_lock(&priv->clk_mutex); + priv->update_clk_rate = true; + drm_crtc_wait_one_vblank(&priv->crtc); + return NOTIFY_OK; + default: + mutex_unlock(&priv->clk_mutex); + return NOTIFY_OK; + } +} + static void ingenic_drm_crtc_atomic_enable(struct drm_crtc *crtc, struct drm_crtc_state *state) { @@ -284,8 +323,14 @@ static void ingenic_drm_crtc_atomic_flush(struct drm_crtc *crtc, if (drm_atomic_crtc_needs_modeset(state)) { ingenic_drm_crtc_update_timings(priv, &state->mode); + priv->update_clk_rate = true; + } + if (priv->update_clk_rate) { + mutex_lock(&priv->clk_mutex); clk_set_rate(priv->pix_clk, state->adjusted_mode.clock * 1000); + priv->update_clk_rate = false; + mutex_unlock(&priv->clk_mutex); } if (event) { @@ -1044,16 +1089,28 @@ static int ingenic_drm_bind(struct device *dev, bool has_components) if (soc_info->has_osd) regmap_write(priv->map, JZ_REG_LCD_OSDC, JZ_LCD_OSDC_OSDEN); + mutex_init(&priv->clk_mutex); + priv->clock_nb.notifier_call = ingenic_drm_update_pixclk; + + parent_clk = clk_get_parent(priv->pix_clk); + ret = clk_notifier_register(parent_clk, &priv->clock_nb); + if (ret) { + dev_err(dev, "Unable to register clock notifier\n"); + goto err_devclk_disable; + } + ret = drm_dev_register(drm, 0); if (ret) { dev_err(dev, "Failed to register DRM driver\n"); - goto err_devclk_disable; + goto err_clk_notifier_unregister; } drm_fbdev_generic_setup(drm, 32); return 0; +err_clk_notifier_unregister: + clk_notifier_unregister(parent_clk, &priv->clock_nb); err_devclk_disable: if (priv->lcd_clk) clk_disable_unprepare(priv->lcd_clk); @@ -1075,7 +1132,9 @@ static int compare_of(struct device *dev, void *data) static void ingenic_drm_unbind(struct device *dev) { struct ingenic_drm *priv = dev_get_drvdata(dev); + struct clk *parent_clk = clk_get_parent(priv->pix_clk); + clk_notifier_unregister(parent_clk, &priv->clock_nb); if (priv->lcd_clk) clk_disable_unprepare(priv->lcd_clk); clk_disable_unprepare(priv->pix_clk);