kernel/linux.git/drivers/firewire/core-card.c, branch v6.6.131

firewire: core: use long bus reset on gap count error

2024-03-26T22:19:14+00:00

[ Upstream commit d0b06dc48fb15902d7da09c5c0861e7f042a9381 ] When resetting the bus after a gap count error, use a long rather than short bus reset. IEEE 1394-1995 uses only long bus resets. IEEE 1394a adds the option of short bus resets. When video or audio transmission is in progress and a device is hot-plugged elsewhere on the bus, the resulting bus reset can cause video frame drops or audio dropouts. Short bus resets reduce or eliminate this problem. Accordingly, short bus resets are almost always preferred. However, on a mixed 1394/1394a bus, a short bus reset can trigger an immediate additional bus reset. This double bus reset can be interpreted differently by different nodes on the bus, resulting in an inconsistent gap count after the bus reset. An inconsistent gap count will cause another bus reset, leading to a neverending bus reset loop. This only happens for some bus topologies, not for all mixed 1394/1394a buses. By instead sending a long bus reset after a gap count inconsistency, we avoid the doubled bus reset, restoring the bus to normal operation. Signed-off-by: Adam Goldman Link: https://sourceforge.net/p/linux1394/mailman/message/58741624/ Signed-off-by: Takashi Sakamoto Signed-off-by: Sasha Levin

firewire: core: send bus reset promptly on gap count error

2024-03-01T12:34:56+00:00

[ Upstream commit 7ed4380009e96d9e9c605e12822e987b35b05648 ] If we are bus manager and the bus has inconsistent gap counts, send a bus reset immediately instead of trying to read the root node's config ROM first. Otherwise, we could spend a lot of time trying to read the config ROM but never succeeding. This eliminates a 50+ second delay before the FireWire bus is usable after a newly connected device is powered on in certain circumstances. The delay occurs if a gap count inconsistency occurs, we are not the root node, and we become bus manager. One scenario that causes this is with a TI XIO2213B OHCI, the first time a Sony DSR-25 is powered on after being connected to the FireWire cable. In this configuration, the Linux box will not receive the initial PHY configuration packet sent by the DSR-25 as IRM, resulting in the DSR-25 having a gap count of 44 while the Linux box has a gap count of 63. FireWire devices have a gap count parameter, which is set to 63 on power-up and can be changed with a PHY configuration packet. This determines the duration of the subaction and arbitration gaps. For reliable communication, all nodes on a FireWire bus must have the same gap count. A node may have zero or more of the following roles: root node, bus manager (BM), isochronous resource manager (IRM), and cycle master. Unless a root node was forced with a PHY configuration packet, any node might become root node after a bus reset. Only the root node can become cycle master. If the root node is not cycle master capable, the BM or IRM should force a change of root node. After a bus reset, each node sends a self-ID packet, which contains its current gap count. A single bus reset does not change the gap count, but two bus resets in a row will set the gap count to 63. Because a consistent gap count is required for reliable communication, IEEE 1394a-2000 requires that the bus manager generate a bus reset if it detects that the gap count is inconsistent. When the gap count is inconsistent, build_tree() will notice this after the self identification process. It will set card->gap_count to the invalid value 0. If we become bus master, this will force bm_work() to send a bus reset when it performs gap count optimization. After a bus reset, there is no bus manager. We will almost always try to become bus manager. Once we become bus manager, we will first determine whether the root node is cycle master capable. Then, we will determine if the gap count should be changed. If either the root node or the gap count should be changed, we will generate a bus reset. To determine if the root node is cycle master capable, we read its configuration ROM. bm_work() will wait until we have finished trying to read the configuration ROM. However, an inconsistent gap count can make this take a long time. read_config_rom() will read the first few quadlets from the config ROM. Due to the gap count inconsistency, eventually one of the reads will time out. When read_config_rom() fails, fw_device_init() calls it again until MAX_RETRIES is reached. This takes 50+ seconds. Once we give up trying to read the configuration ROM, bm_work() will wake up, assume that the root node is not cycle master capable, and do a bus reset. Hopefully, this will resolve the gap count inconsistency. This change makes bm_work() check for an inconsistent gap count before waiting for the root node's configuration ROM. If the gap count is inconsistent, bm_work() will immediately do a bus reset. This eliminates the 50+ second delay and rapidly brings the bus to a working state. I considered that if the gap count is inconsistent, a PHY configuration packet might not be successful, so it could be desirable to skip the PHY configuration packet before the bus reset in this case. However, IEEE 1394a-2000 and IEEE 1394-2008 say that the bus manager may transmit a PHY configuration packet before a bus reset when correcting a gap count error. Since the standard endorses this, I decided it's safe to retain the PHY configuration packet transmission. Normally, after a topology change, we will reset the bus a maximum of 5 times to change the root node and perform gap count optimization. However, if there is a gap count inconsistency, we must always generate a bus reset. Otherwise the gap count inconsistency will persist and communication will be unreliable. For that reason, if there is a gap count inconstency, we generate a bus reset even if we already reached the 5 reset limit. Signed-off-by: Adam Goldman Reference: https://sourceforge.net/p/linux1394/mailman/message/58727806/ Signed-off-by: Takashi Sakamoto Signed-off-by: Sasha Levin

Merge branch 'for-linus' into for-next

2022-05-23T05:48:27+00:00

Merge for 5.18-rc1 Signed-off-by: Takashi Iwai

firewire: core: extend card->lock in fw_core_handle_bus_reset

2022-04-25T06:01:09+00:00

card->local_node and card->bm_retries are both always accessed under card->lock. fw_core_handle_bus_reset has a check whose condition depends on card->local_node and whose body writes to card->bm_retries. Both of these accesses are not under card->lock. Move the lock acquiring of card->lock to before this check such that these accesses do happen when card->lock is held. fw_destroy_nodes is called inside the check. Since fw_destroy_nodes already acquires card->lock inside its function body, move this out to the callsites of fw_destroy_nodes. Also add a comment to indicate which locking is necessary when calling fw_destroy_nodes. Cc: Signed-off-by: Niels Dossche Signed-off-by: Takashi Sakamoto Link: https://lore.kernel.org/r/20220409041243.603210-4-o-takashi@sakamocchi.jp Signed-off-by: Takashi Iwai

firewire: add kernel API to access CYCLE_TIME register

2022-04-05T16:23:04+00:00

1394 OHCI specification defined Isochronous Cycle Timer Register to get value of CYCLE_TIME register defined by IEEE 1394 for CSR architecture defined by ISO/IEC 13213. Unit driver can calculate packet time by compute with the value of CYCLE_TIME and timeStamp field in descriptor of each isochronous and asynchronous context. The resolution of CYCLE_TIME is 49.576 MHz, while the one of timeStamp is 8,000 Hz. Current implementation of Linux FireWire subsystem allows the driver to get the value of CYCLE_TIMER CSR register by transaction service. The transaction service has overhead in regard of access to MMIO register. This commit adds kernel API for unit driver to access the register directly. Signed-off-by: Takashi Sakamoto Link: https://lore.kernel.org/r/20220405072221.226217-3-o-takashi@sakamocchi.jp Signed-off-by: Takashi Iwai

firewire: Add dummy read_csr/write_csr functions

2022-04-05T16:23:03+00:00

(Hector Martin wrote) This fixes segfaults when a card gets yanked off of the PCIe bus while busy, e.g. with a userspace app trying to get the cycle time: [8638860.994310] Call Trace: [8638860.994313] ioctl_get_cycle_timer2+0x4f/0xd0 [firewire_core] [8638860.994323] fw_device_op_ioctl+0xae/0x150 [firewire_core] [8638860.994328] __x64_sys_ioctl+0x7d/0xb0 [8638860.994332] do_syscall_64+0x45/0x80 [8638860.994337] entry_SYSCALL_64_after_hwframe+0x44/0xae (Takashi Sakamoto wrote) As long as reading commit 20802224298c ("firewire: core: add forgotten dummy driver methods, remove unused ones"), three functions are not implemeted in dummy driver for reason; .read_csr, .write_csr, and .set_config_rom. In core of Linux FireWire subsystem, the callback of .set_config_rom is under acquisition of mutual exclusive for local list of card. The acquision is also done in process for removal of card, therefore it's safe for missing implementation of .set_config_rom. On the other hand, no lock primitive accompanies any call of .read_csr and .write_csr. For userspace client, check of node shutdown is done in the beginning of dispatch of ioctl request, while node shifts to shutdown state in workqueue context enough after card shifts to dummy driver. It's probable that these two functions are called for the dummy driver by the code of userspace client. In-kernel unit driver has similar situation. It's better to add implementation of the two functions for dummy driver. Signed-off-by: Hector Martin Signed-off-by: Takashi Sakamoto Link: https://lore.kernel.org/r/20220405072221.226217-2-o-takashi@sakamocchi.jp Signed-off-by: Takashi Iwai

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

2019-05-30T18:26:35+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1334 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Richard Fontana Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman

Merge tag 'firewire-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394

2012-05-24T19:57:47+00:00

Pull IEEE 1394 (FireWire) subsystem updates from Stefan Richter: - Fix mismatch between DMA mapping direction (was wrong) and DMA synchronization direction (was correct) of isochronous reception buffers of userspace drivers if vma-mapped for R/W access. For example, libdc1394 was affected. - more consistent retry stategy in device discovery/ rediscovery, and improved failure diagnostics - various small cleanups, e.g. use SCSI layer's DMA mapping API in firewire-sbp2 * tag 'firewire-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394: firewire: sbp2: document the absence of alignment requirements firewire: sbp2: remove superfluous blk_queue_max_segment_size() call firewire: sbp2: use scsi_dma_(un)map firewire: sbp2: give correct DMA device to scsi framework firewire: core: fw_device_refresh(): clean up error handling firewire: core: log config rom reading errors firewire: core: log error in case of failed bus manager lock firewire: move rcode_string() to core firewire: core: improve reread_config_rom() interface firewire: core: wait for inaccessible devices after bus reset firewire: ohci: omit spinlock IRQ flags where possible firewire: ohci: correct signedness of a local variable firewire: core: fix DMA mapping direction firewire: use module_pci_driver

firewire: Move fw_card kref functions into linux/firewire.h

2012-05-09T22:25:17+00:00

When writing a firewire driver that doesn't deal with struct fw_device objects (e.g. it only publishes FireWire units and doesn't subscribe to them), you likely need to keep referenced to struct fw_card objects so that you can send messages to other nodes. This patch moves fw_card_put(), fw_card_get() and fw_card_release() into the public include/linux/firewire.h header instead of drivers/firewire/core.h, and adds EXPORT_SYMBOL_GPL(fw_card_release). The firewire-sbp-target module requires these so it can keep a reference to the fw_card object in order that it can fetch ORBs to execute and read/write related data and status information. Signed-off-by: Chris Boot Acked-by: Stefan Richter Cc: Clemens Ladisch Signed-off-by: Nicholas Bellinger

firewire: core: log error in case of failed bus manager lock

2012-04-17T20:56:53+00:00

If the lock access to the bus manager register fails, also log the actual error that caused it to fail. Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter