From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:51194 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031487AbeEZKDF (ORCPT ); Sat, 26 May 2018 06:03:05 -0400 Subject: Re: [PATCH v1] media: staging: tegra-vde: Reset memory client From: Dmitry Osipenko To: Hans Verkuil , Mauro Carvalho Chehab , Thierry Reding , Jonathan Hunter Cc: linux-tegra@vger.kernel.org, linux-media@vger.kernel.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org References: <20180520134846.31046-1-digetx@gmail.com> <20180520134846.31046-2-digetx@gmail.com> Message-ID: <24810d9d-eede-f9dd-1dbe-e757cfa2e191@gmail.com> Date: Sat, 26 May 2018 13:03:01 +0300 MIME-Version: 1.0 In-Reply-To: <20180520134846.31046-2-digetx@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 20.05.2018 16:48, Dmitry Osipenko wrote: > DMA requests must be blocked before resetting VDE HW, otherwise it is > possible to get a memory corruption or a machine hang. Use the reset > control provided by the Memory Controller to block DMA before resetting > the VDE HW. > > Signed-off-by: Dmitry Osipenko > --- > drivers/staging/media/tegra-vde/tegra-vde.c | 42 +++++++++++++++++++-- > 1 file changed, 38 insertions(+), 4 deletions(-) > > diff --git a/drivers/staging/media/tegra-vde/tegra-vde.c b/drivers/staging/media/tegra-vde/tegra-vde.c > index 90177a59b97c..6dd3bf4481be 100644 > --- a/drivers/staging/media/tegra-vde/tegra-vde.c > +++ b/drivers/staging/media/tegra-vde/tegra-vde.c > @@ -73,6 +73,7 @@ struct tegra_vde { > struct mutex lock; > struct miscdevice miscdev; > struct reset_control *rst; > + struct reset_control *rst_mc; > struct gen_pool *iram_pool; > struct completion decode_completion; > struct clk *clk; > @@ -850,9 +851,23 @@ static int tegra_vde_ioctl_decode_h264(struct tegra_vde *vde, > * We rely on the VDE registers reset value, otherwise VDE > * causes bus lockup. > */ > + ret = reset_control_assert(vde->rst_mc); > + if (ret) { > + dev_err(dev, "DEC start: Failed to assert MC reset: %d\n", > + ret); > + goto put_runtime_pm; > + } > + > ret = reset_control_reset(vde->rst); > if (ret) { > - dev_err(dev, "Failed to reset HW: %d\n", ret); > + dev_err(dev, "DEC start: Failed to reset HW: %d\n", ret); > + goto put_runtime_pm; > + } > + > + ret = reset_control_deassert(vde->rst_mc); > + if (ret) { > + dev_err(dev, "DEC start: Failed to deassert MC reset: %d\n", > + ret); > goto put_runtime_pm; > } > > @@ -880,9 +895,21 @@ static int tegra_vde_ioctl_decode_h264(struct tegra_vde *vde, > ret = timeout; > } > > - err = reset_control_assert(vde->rst); > - if (err) > - dev_err(dev, "Failed to assert HW reset: %d\n", err); > + /* > + * At first reset memory client to avoid resetting VDE HW in the > + * middle of DMA which could result into memory corruption or hang > + * the whole system. > + */ > + err = reset_control_assert(vde->rst_mc); > + if (!err) { It occurred to me that there is no need to skip the HW reset if MC resetting fails. I'll make V2 to change that. > + err = reset_control_assert(vde->rst); > + if (err) > + dev_err(dev, > + "DEC end: Failed to assert HW reset: %d\n", > + err); > + } else { > + dev_err(dev, "DEC end: Failed to assert MC reset: %d\n", err); > + } > > put_runtime_pm: > pm_runtime_mark_last_busy(dev); > @@ -1074,6 +1101,13 @@ static int tegra_vde_probe(struct platform_device *pdev) > return err; > } > > + vde->rst_mc = devm_reset_control_get_optional(dev, "mc"); > + if (IS_ERR(vde->rst_mc)) { > + err = PTR_ERR(vde->rst_mc); > + dev_err(dev, "Could not get MC reset %d\n", err); > + return err; > + } > + > irq = platform_get_irq_byname(pdev, "sync-token"); > if (irq < 0) > return irq; >