From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="FyrYhzoY" Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F726B9; Wed, 13 Dec 2023 23:07:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1702537670; x=1734073670; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=aVTV69PCQTQ31JKv3NEFHclx9YKwGXb979KUPDnem7A=; b=FyrYhzoYVAlak9P/SHd5MUELxrxEUz+NizWUWsYbsEUd7tdXpRZkXplB Ha1yNPiucaNflTB618FmEfgSeuki+n63YcB0JapxkBk2SSoTePmCdwIMw PyB3m+nbzWUaDUVp9g6/+5mRgCh8wZmsgT6TBxJMdcTMFez1Oxz3kbHr4 mHl95GFfwSn+VeVnQwb+Z8TamBtK5DKLrUZx2FiS0k16Liq+UqWEOvGMS PTU3NUGYkWThfEDOBvblb1l1KwbwmrVucSGyRi0haVZ0CKv71eYkIxEfz w905+gX/5QBjPV2DwzaDT+UDI/TAIpfWThYFDuhETuDiDxGRdBIOTZSwS A==; X-IronPort-AV: E=McAfee;i="6600,9927,10923"; a="426211181" X-IronPort-AV: E=Sophos;i="6.04,274,1695711600"; d="scan'208";a="426211181" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Dec 2023 23:07:50 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10923"; a="840169997" X-IronPort-AV: E=Sophos;i="6.04,274,1695711600"; d="scan'208";a="840169997" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga008.fm.intel.com with ESMTP; 13 Dec 2023 23:07:48 -0800 Received: by black.fi.intel.com (Postfix, from userid 1001) id CAECD483; Thu, 14 Dec 2023 09:07:46 +0200 (EET) Date: Thu, 14 Dec 2023 09:07:46 +0200 From: Mika Westerberg To: Sanath S Cc: Sanath S , mario.limonciello@amd.com, andreas.noever@gmail.com, michael.jamet@intel.com, YehezkelShB@gmail.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [Patch v2 2/2] thunderbolt: Teardown tunnels and reset downstream ports created by boot firmware Message-ID: <20231214070746.GS1074920@black.fi.intel.com> References: <20231212191635.2022520-1-Sanath.S@amd.com> <20231212191635.2022520-3-Sanath.S@amd.com> <20231213054914.GI1074920@black.fi.intel.com> <20231213061805.GK1074920@black.fi.intel.com> <20231213062306.GL1074920@black.fi.intel.com> <20231213115256.GM1074920@black.fi.intel.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Dec 14, 2023 at 12:08:34PM +0530, Sanath S wrote: > > On 12/13/2023 5:22 PM, Mika Westerberg wrote: > > On Wed, Dec 13, 2023 at 04:04:57PM +0530, Sanath S wrote: > > > On 12/13/2023 11:53 AM, Mika Westerberg wrote: > > > > On Wed, Dec 13, 2023 at 08:18:06AM +0200, Mika Westerberg wrote: > > > > > On Wed, Dec 13, 2023 at 07:49:14AM +0200, Mika Westerberg wrote: > > > > > > On Wed, Dec 13, 2023 at 12:46:35AM +0530, Sanath S wrote: > > > > > > > Boot firmware might have created tunnels of its own. Since we cannot > > > > > > > be sure they are usable for us. Tear them down and reset the ports > > > > > > > to handle it as a new hotplug for USB3 routers. > > > > > > > > > > > > > > Suggested-by: Mario Limonciello > > > > > > > Signed-off-by: Sanath S > > > > > > > --- > > > > > > > drivers/thunderbolt/tb.c | 11 +++++++++++ > > > > > > > 1 file changed, 11 insertions(+) > > > > > > > > > > > > > > diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c > > > > > > > index fd49f86e0353..febd0b6972e3 100644 > > > > > > > --- a/drivers/thunderbolt/tb.c > > > > > > > +++ b/drivers/thunderbolt/tb.c > > > > > > > @@ -2598,6 +2598,17 @@ static int tb_start(struct tb *tb) > > > > > > > tb_switch_tmu_enable(tb->root_switch); > > > > > > > /* Full scan to discover devices added before the driver was loaded. */ > > > > > > > tb_scan_switch(tb->root_switch); > > > > > > > + /* > > > > > > > + * Boot firmware might have created tunnels of its own. Since we cannot > > > > > > > + * be sure they are usable for us, Tear them down and reset the ports > > > > > > > + * to handle it as new hotplug for USB4 routers. > > > > > > > + */ > > > > > > > + if (tb_switch_is_usb4(tb->root_switch)) { > > > > > > > + tb_switch_discover_tunnels(tb->root_switch, > > > > > > > + &tcm->tunnel_list, false); > > > > > > Why this is needed? > > > > > > > > > > > > It should be enough, to do simply something like this: > > > > > > > > > > > > if (tb_switch_is_usb4(tb->root_switch)) > > > > > > tb_switch_reset(tb->root_switch); > > > If we don't tear down of tunnels before performing the DPR, the PCIe > > > enumeration is failing. > > > > > > PCIe link is not coming up after DPR. Below log is missing without > > > performing path > > > deactivation before performing DPR and hence PCIe enumeration is not > > > initiated. > > > > > > [  746.630865] pcieport 0000:00:03.1: pciehp: Slot(0-1): Card present > > > [  746.630885] pcieport 0000:00:03.1: pciehp: Slot(0-1): Link Up > > > > > > I think when we do a DPR, it internally does some handling with PCI Path > > > Enable bit(PE). > > > So, deactivation of PCIe path is necessary for DPR to work. > > Rigth, it should be enough to reset the protocol adapter config and path > > config spaces. I guess using discovery at this point is fine too but I > > would at least check how complex doing the minimal "reset" turns out. > > > > I mean in tb_switch_reset() for USB4 v1 routers it can go over all the > > adapters and perform "cleanup" or so. > I gave it a thought yesterday and we can do something like this: > > We are already doing tb_discovery(tb) in tb_start. This would > discover the path configuration done by Boot firmware. > > Now, we can place the tb_switch_reset() right below that api with > conditions suggested by you. > > And tb_switch_reset() would internally DPR for all down steam ports. > > It can look something like below: > >     /* Find out tunnels created by the boot firmware */ >         tb_discover_tunnels(tb); >     /* >      * Reset USB4 v1 host router to get rid of possible tunnels the >      * boot firmware created. This makes sure all the tunnels are >      * created by us and thus have known configuration. >      * >      * For USB4 v2 and beyond we do this in nhi_reset() using the >      * host router reset interface. >      */ >     if (host_reset && usb4_switch_version(tb->root_switch) == 1) >         tb_switch_reset(tb->root_switch); > > With this, we are making sure while we get a unplug event after doing a DPR, > We are clearing all the paths established by Boot firmware. This wouldn't be > possible > if we had not discovered the paths before we perform DPR. > > It would create inconsistency for a new hot plug if we have not cleared the > path configurations > of previous hot unplug events. Right. I would still check if doing protocol adapter "reset" + path config space clear in tb_switch_reset() is enough and how complex that ends up to be. I think that's all what is needed. If it turns out too complex, yes I guess something like this: /* Find out tunnels created by the boot firmware */ tb_discover_tunnels(tb); /* Add DP resources from the DP tunnels created by the boot firmware */ tb_discover_dp_resources(tb); if (host_reset && usb4_switch_version(tb->root_switch) == 1) { struct tb_tunnel *n, *tunnel; list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list) tb_deactivate_and_free_tunnel(tunnel); tb_switch_reset(tb->root_switch); } With proper comments would work, no? Regarding "host_reset", I think we can actually keep it in nhi.c and add a parameter to cm_ops->start(reset) that gets passed to the "CM implementation". Or something along those lines. > > > > > Actually this needs to be done only for USB4 v1 routers since we already > > > > > reset USB4 v2 hosts so something like: > > > > > > > > > > /* > > > > > * Reset USB4 v1 host router to get rid of possible tunnels the > > > > > * boot firmware created. This makes sure all the tunnels are > > > > > * created by us and thus have known configuration. > > > > > * > > > > > * For USB4 v2 and beyond we do this in nhi_reset() using the > > > > > * host router reset interface. > > > > > */ > > > > > if (usb4_switch_version(tb->root_switch) == 1) > > > > > tb_switch_reset(tb->root_switch); > > > > > > > > > > (possibly add similar comment to the nhi_reset() to refer this one). > > > > Oh, and would it be possible to tie this with the "host_reset" parameter > > > > too somehow? I guess it could be moved to "tb.c" and "tb.h" and then > > > > check it from nhi.c as already done and then here so this would become: > > > > > > > > if (host_reset && usb4_switch_version(tb->root_switch) == 1) > > > > tb_switch_reset(tb->root_switch); > > > Is host_reset necessary for USB4 v1 routers ? I did not use host_reset in > > > this case. > > > If its needed, then we have to modify to enable host_reset in nhi.c as well. > > Well you are effectively doing that here, no? You "reset" the host > > router therefore tying this to the same command line parameter makes > > sense and allows user an "escape hatch" if this turns out breaking > > things.