From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66CB5C4332B for ; Mon, 23 Mar 2020 22:50:33 +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 308C620714 for ; Mon, 23 Mar 2020 22:50:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=agner.ch header.i=@agner.ch header.b="P22pCz5K" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 308C620714 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=agner.ch 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 5133F6E054; Mon, 23 Mar 2020 22:50:32 +0000 (UTC) Received: from mail.kmu-office.ch (mail.kmu-office.ch [IPv6:2a02:418:6a02::a2]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8DACA6E054 for ; Mon, 23 Mar 2020 22:50:30 +0000 (UTC) Received: from webmail.kmu-office.ch (unknown [IPv6:2a02:418:6a02::a3]) by mail.kmu-office.ch (Postfix) with ESMTPSA id 28D8E5C061C; Mon, 23 Mar 2020 23:50:29 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=agner.ch; s=dkim; t=1585003829; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=eaeWtPrfBPzeXFIzWk/wbpzN8v46/3MPxsutBGPSJ1Q=; b=P22pCz5K3FGJxktMZC4pVMxnD+YFFqtQlxAMobhfSTW4/jYK1ZEyarF9opMVwoK3Xacewg oCEP+xIE81QFqld41M4TIHzFwjsroezch2jDnFSlcZQFn3n1ZA6l5A5DiSTPqjb1ZelTl7 14gIhPY6qf1FAZVTEqVIMIuun0xj82Q= MIME-Version: 1.0 Date: Mon, 23 Mar 2020 23:50:29 +0100 From: Stefan Agner To: Laurent Pinchart Subject: Re: [PATCH 13/21] drm: mxsfb: Don't touch AXI clock in IRQ context In-Reply-To: <20200309195216.31042-14-laurent.pinchart@ideasonboard.com> References: <20200309195216.31042-1-laurent.pinchart@ideasonboard.com> <20200309195216.31042-14-laurent.pinchart@ideasonboard.com> User-Agent: Roundcube Webmail/1.4.1 Message-ID: X-Sender: stefan@agner.ch 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: Marek Vasut , kernel@pengutronix.de, dri-devel@lists.freedesktop.org, linux-imx@nxp.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 2020-03-09 20:52, Laurent Pinchart wrote: > The driver attempts agressive power management by enabling and disabling > the AXI clock around register accesses. This results in attempts to > enable and disable the clock in the IRQ handler, which is a no-go as > preparing or unpreparing the clock may sleep. > > On the other hand, the driver enables the AXI clock when enabling the > CRTC and keeps it enabled until the CRTC is disabled. This is correct, > and renders the power management attempt pointless, as interrupts are > not supposed to occur when the CRTC is off. > > The same reasoning can be applied to the CRTC .enable_vblank() and > .disable_vblank() that are not supposed to be called when the CRTC off > and thus don't require manual handling of the AXI clock. Furthermore, > vblank handling is never enabled, which results in the vblank enable and > disable handlers never being called. > > To fix this, remove the manual clock handling in the IRQ, the CRTC > .enable_vblank() and .disable_vblank() handlers and the plane > .atomic_update() handler. We however need to handle the clock manually > in mxsfb_irq_disable() as is calls .disable_vblank() manually and is > used both at probe and remove time. > > The clock disabling is also moved to the last step of the > mxsfb_crtc_atomic_disable() function, to prepare for enabling vblank > handling. > > Signed-off-by: Laurent Pinchart Looks good to me! Reviewed-by: Stefan Agner > --- > drivers/gpu/drm/mxsfb/mxsfb_drv.c | 6 ++---- > drivers/gpu/drm/mxsfb/mxsfb_kms.c | 15 ++++----------- > 2 files changed, 6 insertions(+), 15 deletions(-) > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c > b/drivers/gpu/drm/mxsfb/mxsfb_drv.c > index a8da92976d13..e324bd2a63a5 100644 > --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c > +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c > @@ -231,7 +231,9 @@ static void mxsfb_irq_disable(struct drm_device *drm) > { > struct mxsfb_drm_private *mxsfb = drm->dev_private; > > + mxsfb_enable_axi_clk(mxsfb); > mxsfb->crtc.funcs->disable_vblank(&mxsfb->crtc); > + mxsfb_disable_axi_clk(mxsfb); > } > > static irqreturn_t mxsfb_irq_handler(int irq, void *data) > @@ -240,8 +242,6 @@ static irqreturn_t mxsfb_irq_handler(int irq, void *data) > struct mxsfb_drm_private *mxsfb = drm->dev_private; > u32 reg; > > - mxsfb_enable_axi_clk(mxsfb); > - > reg = readl(mxsfb->base + LCDC_CTRL1); > > if (reg & CTRL1_CUR_FRAME_DONE_IRQ) > @@ -249,8 +249,6 @@ static irqreturn_t mxsfb_irq_handler(int irq, void *data) > > writel(CTRL1_CUR_FRAME_DONE_IRQ, mxsfb->base + LCDC_CTRL1 + REG_CLR); > > - mxsfb_disable_axi_clk(mxsfb); > - > return IRQ_HANDLED; > } > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c > b/drivers/gpu/drm/mxsfb/mxsfb_kms.c > index ebe0785694cb..ac2696c8483d 100644 > --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c > +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c > @@ -344,9 +344,6 @@ static void mxsfb_crtc_atomic_disable(struct drm_crtc *crtc, > struct drm_pending_vblank_event *event; > > mxsfb_disable_controller(mxsfb); > - mxsfb_disable_axi_clk(mxsfb); > - > - pm_runtime_put_sync(drm->dev); > > spin_lock_irq(&drm->event_lock); > event = crtc->state->event; > @@ -355,6 +352,9 @@ static void mxsfb_crtc_atomic_disable(struct drm_crtc *crtc, > drm_crtc_send_vblank_event(crtc, event); > } > spin_unlock_irq(&drm->event_lock); > + > + mxsfb_disable_axi_clk(mxsfb); > + pm_runtime_put_sync(drm->dev); > } > > static int mxsfb_crtc_enable_vblank(struct drm_crtc *crtc) > @@ -362,10 +362,8 @@ static int mxsfb_crtc_enable_vblank(struct drm_crtc *crtc) > struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev); > > /* Clear and enable VBLANK IRQ */ > - mxsfb_enable_axi_clk(mxsfb); > writel(CTRL1_CUR_FRAME_DONE_IRQ, mxsfb->base + LCDC_CTRL1 + REG_CLR); > writel(CTRL1_CUR_FRAME_DONE_IRQ_EN, mxsfb->base + LCDC_CTRL1 + REG_SET); > - mxsfb_disable_axi_clk(mxsfb); > > return 0; > } > @@ -375,10 +373,8 @@ static void mxsfb_crtc_disable_vblank(struct > drm_crtc *crtc) > struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev); > > /* Disable and clear VBLANK IRQ */ > - mxsfb_enable_axi_clk(mxsfb); > writel(CTRL1_CUR_FRAME_DONE_IRQ_EN, mxsfb->base + LCDC_CTRL1 + REG_CLR); > writel(CTRL1_CUR_FRAME_DONE_IRQ, mxsfb->base + LCDC_CTRL1 + REG_CLR); > - mxsfb_disable_axi_clk(mxsfb); > } > > static const struct drm_crtc_helper_funcs mxsfb_crtc_helper_funcs = { > @@ -433,11 +429,8 @@ static void mxsfb_plane_atomic_update(struct > drm_plane *plane, > dma_addr_t paddr; > > paddr = mxsfb_get_fb_paddr(mxsfb); > - if (paddr) { > - mxsfb_enable_axi_clk(mxsfb); > + if (paddr) > writel(paddr, mxsfb->base + mxsfb->devdata->next_buf); > - mxsfb_disable_axi_clk(mxsfb); > - } > } > > static const struct drm_plane_helper_funcs mxsfb_plane_helper_funcs = { _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel