LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Serge Semin <Sergey.Semin@baikalelectronics.ru>,
	Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: [PATCH 4.4 18/35] usb: dwc3: ulpi: Replace CPU-based busyloop with Protocol-based one
Date: Mon, 22 Feb 2021 13:36:14 +0100
Message-ID: <20210222121020.129125658@linuxfoundation.org> (raw)
In-Reply-To: <20210222121013.581198717@linuxfoundation.org>

From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

commit fca3f138105727c3a22edda32d02f91ce1bf11c9 upstream

Originally the procedure of the ULPI transaction finish detection has been
developed as a simple busy-loop with just decrementing counter and no
delays. It's wrong since on different systems the loop will take a
different time to complete. So if the system bus and CPU are fast enough
to overtake the ULPI bus and the companion PHY reaction, then we'll get to
take a false timeout error. Fix this by converting the busy-loop procedure
to take the standard bus speed, address value and the registers access
mode into account for the busy-loop delay calculation.

Here is the way the fix works. It's known that the ULPI bus is clocked
with 60MHz signal. In accordance with [1] the ULPI bus protocol is created
so to spend 5 and 6 clock periods for immediate register write and read
operations respectively, and 6 and 7 clock periods - for the extended
register writes and reads. Based on that we can easily pre-calculate the
time which will be needed for the controller to perform a requested IO
operation. Note we'll still preserve the attempts counter in case if the
DWC USB3 controller has got some internals delays.

[1] UTMI+ Low Pin Interface (ULPI) Specification, Revision 1.1,
    October 20, 2004, pp. 30 - 36.

Fixes: 88bc9d194ff6 ("usb: dwc3: add ULPI interface support")
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210085008.13264-3-Sergey.Semin@baikalelectronics.ru
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/dwc3/ulpi.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

--- a/drivers/usb/dwc3/ulpi.c
+++ b/drivers/usb/dwc3/ulpi.c
@@ -10,6 +10,8 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/delay.h>
+#include <linux/time64.h>
 #include <linux/ulpi/regs.h>
 
 #include "core.h"
@@ -20,12 +22,22 @@
 		DWC3_GUSB2PHYACC_ADDR(ULPI_ACCESS_EXTENDED) | \
 		DWC3_GUSB2PHYACC_EXTEND_ADDR(a) : DWC3_GUSB2PHYACC_ADDR(a))
 
-static int dwc3_ulpi_busyloop(struct dwc3 *dwc)
+#define DWC3_ULPI_BASE_DELAY	DIV_ROUND_UP(NSEC_PER_SEC, 60000000L)
+
+static int dwc3_ulpi_busyloop(struct dwc3 *dwc, u8 addr, bool read)
 {
+	unsigned long ns = 5L * DWC3_ULPI_BASE_DELAY;
 	unsigned int count = 1000;
 	u32 reg;
 
+	if (addr >= ULPI_EXT_VENDOR_SPECIFIC)
+		ns += DWC3_ULPI_BASE_DELAY;
+
+	if (read)
+		ns += DWC3_ULPI_BASE_DELAY;
+
 	while (count--) {
+		ndelay(ns);
 		reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYACC(0));
 		if (!(reg & DWC3_GUSB2PHYACC_BUSY))
 			return 0;
@@ -44,7 +56,7 @@ static int dwc3_ulpi_read(struct ulpi_op
 	reg = DWC3_GUSB2PHYACC_NEWREGREQ | DWC3_ULPI_ADDR(addr);
 	dwc3_writel(dwc->regs, DWC3_GUSB2PHYACC(0), reg);
 
-	ret = dwc3_ulpi_busyloop(dwc);
+	ret = dwc3_ulpi_busyloop(dwc, addr, true);
 	if (ret)
 		return ret;
 
@@ -62,7 +74,7 @@ static int dwc3_ulpi_write(struct ulpi_o
 	reg |= DWC3_GUSB2PHYACC_WRITE | val;
 	dwc3_writel(dwc->regs, DWC3_GUSB2PHYACC(0), reg);
 
-	return dwc3_ulpi_busyloop(dwc);
+	return dwc3_ulpi_busyloop(dwc, addr, false);
 }
 
 static struct ulpi_ops dwc3_ulpi_ops = {



  parent reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-22 12:35 [PATCH 4.4 00/35] 4.4.258-rc1 review Greg Kroah-Hartman
2021-02-22 12:35 ` [PATCH 4.4 01/35] tracing: Do not count ftrace events in top level enable output Greg Kroah-Hartman
2021-02-22 12:35 ` [PATCH 4.4 02/35] fgraph: Initialize tracing_graph_pause at task creation Greg Kroah-Hartman
2021-02-22 12:35 ` [PATCH 4.4 03/35] af_key: relax availability checks for skb size calculation Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 04/35] iwlwifi: pcie: add a NULL check in iwl_pcie_txq_unmap Greg Kroah-Hartman
2021-02-25  6:04   ` Nobuhiro Iwamatsu
2021-02-25  8:14     ` Greg Kroah-Hartman
2021-02-25  8:47       ` Nobuhiro Iwamatsu
2021-02-22 12:36 ` [PATCH 4.4 05/35] iwlwifi: mvm: guard against device removal in reprobe Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 06/35] SUNRPC: Move simple_get_bytes and simple_get_netobj into private header Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 07/35] SUNRPC: Handle 0 length opaque XDR object data properly Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 08/35] lib/string: Add strscpy_pad() function Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 09/35] include/trace/events/writeback.h: fix -Wstringop-truncation warnings Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 10/35] memcg: fix a crash in wb_workfn when a device disappears Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 11/35] squashfs: add more sanity checks in id lookup Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 12/35] squashfs: add more sanity checks in inode lookup Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 13/35] squashfs: add more sanity checks in xattr id lookup Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 14/35] memblock: do not start bottom-up allocations with kernel_end Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 15/35] netfilter: xt_recent: Fix attempt to update deleted entry Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 16/35] h8300: fix PREEMPTION build, TI_PRE_COUNT undefined Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 17/35] usb: dwc3: ulpi: fix checkpatch warning Greg Kroah-Hartman
2021-02-22 12:36 ` Greg Kroah-Hartman [this message]
2021-02-22 12:36 ` [PATCH 4.4 19/35] net: watchdog: hold device global xmit lock during tx disable Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 20/35] vsock: fix locking in vsock_shutdown() Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 21/35] x86/build: Disable CET instrumentation in the kernel for 32-bit too Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 22/35] trace: Use -mcount-record for dynamic ftrace Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 23/35] tracing: Fix SKIP_STACK_VALIDATION=1 build due to bad merge with -mrecord-mcount Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 24/35] tracing: Avoid calling cc-option -mrecord-mcount for every Makefile Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 25/35] Xen/x86: dont bail early from clear_foreign_p2m_mapping() Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 26/35] Xen/x86: also check kernel mapping in set_foreign_p2m_mapping() Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 27/35] Xen/gntdev: correct dev_bus_addr handling in gntdev_map_grant_pages() Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 28/35] Xen/gntdev: correct error checking " Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 29/35] xen/arm: dont ignore return errors from set_phys_to_machine Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 30/35] xen-blkback: dont "handle" error by BUG() Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 31/35] xen-netback: " Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 32/35] xen-scsiback: " Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 33/35] xen-blkback: fix error handling in xen_blkbk_map() Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 34/35] scsi: qla2xxx: Fix crash during driver load on big endian machines Greg Kroah-Hartman
2021-02-22 12:36 ` [PATCH 4.4 35/35] kvm: check tlbs_dirty directly Greg Kroah-Hartman
2021-02-22 18:37 ` [PATCH 4.4 00/35] 4.4.258-rc1 review Pavel Machek
2021-02-22 21:26 ` Guenter Roeck
2021-02-23 12:13 ` Naresh Kamboju
2021-02-23 21:26 ` Shuah Khan

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210222121020.129125658@linuxfoundation.org \
    --to=gregkh@linuxfoundation.org \
    --cc=Sergey.Semin@baikalelectronics.ru \
    --cc=heikki.krogerus@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=sudipm.mukherjee@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git