Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756484AbcJHQAT (ORCPT ); Sat, 8 Oct 2016 12:00:19 -0400 Received: from mga11.intel.com ([192.55.52.93]:47674 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752684AbcJHQAK (ORCPT ); Sat, 8 Oct 2016 12:00:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,461,1473145200"; d="scan'208";a="17560228" Date: Sat, 8 Oct 2016 19:00:06 +0300 From: Jarkko Sakkinen To: "Winkler, Tomas" Cc: "tpmdd-devel@lists.sourceforge.net" , Jason Gunthorpe , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/4] tmp/tpm_crb: fix Intel PTT hw bug during idle state Message-ID: <20161008160006.GA25893@intel.com> References: <1475927979-23484-1-git-send-email-tomas.winkler@intel.com> <1475927979-23484-3-git-send-email-tomas.winkler@intel.com> <20161008125003.GB10317@intel.com> <5B8DA87D05A7694D9FA63FD143655C1B542F6768@hasmsx108.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5B8DA87D05A7694D9FA63FD143655C1B542F6768@hasmsx108.ger.corp.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5170 Lines: 142 On Sat, Oct 08, 2016 at 02:27:06PM +0000, Winkler, Tomas wrote: > > > > On Sat, Oct 08, 2016 at 02:59:37PM +0300, Tomas Winkler wrote: > > > From: "Winkler, Tomas" > > > > > > There is a HW bug in Skylake, Kabylake, and Broxton PCH Intel PTT > > > device, where most of the registers in the control area except START, > > > REQUEST, CANCEL, and LOC_CTRL lost retention when the device is in the > > idle state. > > > Hence we need to bring the device to ready state before accessing the > > > other registers. The fix brings device to ready state before trying to > > > read command and response buffer addresses in order to remap the for > > access. > > > > > > Signed-off-by: Tomas Winkler > > > --- > > > V2: cmd read need to be called also before crb_init as this will run > > > self test. > > > V3: resend. > > > V4: add Kabylake to the list of effected platforms > > > > > > drivers/char/tpm/tpm_crb.c | 47 > > > ++++++++++++++++++++++++++++++++++++++-------- > > > 1 file changed, 39 insertions(+), 8 deletions(-) > > > > > > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c > > > index 0f3b3f3d12d3..4eb96b85c653 100644 > > > --- a/drivers/char/tpm/tpm_crb.c > > > +++ b/drivers/char/tpm/tpm_crb.c > > > @@ -319,6 +319,7 @@ static int crb_map_io(struct acpi_device *device, > > struct crb_priv *priv, > > > struct list_head resources; > > > struct resource io_res; > > > struct device *dev = &device->dev; > > > + u32 pa_high, pa_low; > > > u64 cmd_pa; > > > u32 cmd_size; > > > u64 rsp_pa; > > > @@ -346,12 +347,27 @@ static int crb_map_io(struct acpi_device *device, > > struct crb_priv *priv, > > > if (IS_ERR(priv->cca)) > > > return PTR_ERR(priv->cca); > > > > > > - cmd_pa = ((u64) ioread32(&priv->cca->cmd_pa_high) << 32) | > > > - (u64) ioread32(&priv->cca->cmd_pa_low); > > > + /* > > > + * PTT HW bug w/a: wake up the device to access > > > + * possibly not retained registers. > > > + */ > > > + ret = crb_cmd_ready(dev, priv); > > > + if (ret) > > > + return ret; > > > + > > > + pa_high = ioread32(&priv->cca->cmd_pa_high); > > > + pa_low = ioread32(&priv->cca->cmd_pa_low); > > > + cmd_pa = ((u64)pa_high << 32) | pa_low; > > > cmd_size = ioread32(&priv->cca->cmd_size); > > > + > > > + dev_dbg(dev, "cmd_hi = %X cmd_low = %X cmd_size %X\n", > > > + pa_high, pa_low, cmd_size); > > > + > > > priv->cmd = crb_map_res(dev, priv, &io_res, cmd_pa, cmd_size); > > > - if (IS_ERR(priv->cmd)) > > > - return PTR_ERR(priv->cmd); > > > + if (IS_ERR(priv->cmd)) { > > > + ret = PTR_ERR(priv->cmd); > > > + goto out; > > > + } > > > > > > memcpy_fromio(&rsp_pa, &priv->cca->rsp_pa, 8); > > > rsp_pa = le64_to_cpu(rsp_pa); > > > @@ -359,7 +375,8 @@ static int crb_map_io(struct acpi_device *device, > > > struct crb_priv *priv, > > > > > > if (cmd_pa != rsp_pa) { > > > priv->rsp = crb_map_res(dev, priv, &io_res, rsp_pa, rsp_size); > > > - return PTR_ERR_OR_ZERO(priv->rsp); > > > + ret = PTR_ERR_OR_ZERO(priv->rsp); > > > + goto out; > > > } > > > > > > /* According to the PTP specification, overlapping command and > > > response @@ -367,12 +384,18 @@ static int crb_map_io(struct acpi_device > > *device, struct crb_priv *priv, > > > */ > > > if (cmd_size != rsp_size) { > > > dev_err(dev, FW_BUG "overlapping command and response > > buffer sizes are not identical"); > > > - return -EINVAL; > > > + ret = -EINVAL; > > > + goto out; > > > } > > > + > > > priv->cmd_size = cmd_size; > > > > > > priv->rsp = priv->cmd; > > > - return 0; > > > + > > > +out: > > > + crb_go_idle(dev, priv); > > > + > > > + return ret; > > > } > > > > > > static int crb_acpi_add(struct acpi_device *device) @@ -416,7 +439,15 > > > @@ static int crb_acpi_add(struct acpi_device *device) > > > if (rc) > > > return rc; > > > > > > - return crb_init(device, priv); > > > + rc = crb_cmd_ready(dev, priv); > > > + if (rc) > > > + return rc; > > > > I cannot find any valid reason why crb_map_io calls crb_go_idle in the except > > in the case of a failure. This is something I complained earlier. > > Haven't I've already explained that? Each flow has to be enclosed by > cmdReady and goIdle. There is nothing different here from the other > flows in that matter. The assumption here is that we are starting in > the idle state bug because of the HW bug we cannot access the > registers. So the whole w/o is enclosed in the crb_map_io. After that > we are starting from new, from the idle state. But why you have to do crb_go_idle upon returning from crb_map_io()? > > A minor thing but the extra crb_cmd_ready is basically clutter to the > > initialization. > > The extra cmdReady is here in case runtime pm is not compiled into the > kernel and assumption here is that we are starting in the idle state. > Please remember that unfortunately we cannot detect whether we are in > ready on idle state as the status register is not retained, so > everything has to be ordered properly. Rather you it would be better not to use cmdReady/goIdle at all if kernel is not compiled with CONFIG_PM. > Thanks > Tomas /Jarkko