linux-stable.git/drivers/staging/axis-fifo, branch linux-5.15.y

staging: axis-fifo: flush RX FIFO on read errors

2025-10-19T14:21:28+00:00

commit 82a051e2553b9e297cba82a975d9c538b882c79e upstream.

Flush stale data from the RX FIFO in case of errors, to avoid reading
old data when new packets arrive.

Commit c6e8d85fafa7 ("staging: axis-fifo: Remove hardware resets for
user errors") removed full FIFO resets from the read error paths, which
fixed potential TX data losses, but introduced this RX issue.

Fixes: c6e8d85fafa7 ("staging: axis-fifo: Remove hardware resets for user errors")
Cc: stable@vger.kernel.org
Signed-off-by: Ovidiu Panait 
Link: https://lore.kernel.org/r/20250912101322.1282507-2-ovidiu.panait.oss@gmail.com
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: fix maximum TX packet length check

2025-10-19T14:21:28+00:00

commit 52ff2b840bc723f3be1f096f8017c78e0515858c upstream.

Since commit 2ca34b508774 ("staging: axis-fifo: Correct handling of
tx_fifo_depth for size validation"), write() operations with packets
larger than 'tx_fifo_depth - 4' words are no longer rejected with -EINVAL.

Fortunately, the packets are not actually getting transmitted to hardware,
otherwise they would be raising a 'Transmit Packet Overrun Error'
interrupt, which requires a reset of the TX circuit to recover from.

Instead, the request times out inside wait_event_interruptible_timeout()
and always returns -EAGAIN, since the wake up condition can never be true
for these packets. But still, they unnecessarily block other tasks from
writing to the FIFO and the EAGAIN return code signals userspace to retry
the write() call, even though it will always fail and time out.

According to the AXI4-Stream FIFO reference manual (PG080), the maximum
valid packet length is 'tx_fifo_depth - 4' words, so attempting to send
larger packets is invalid and should not be happening in the first place:

> The maximum packet that can be transmitted is limited by the size of
> the FIFO, which is (C_TX_FIFO_DEPTH–4)*(data interface width/8) bytes.

Therefore, bring back the old behavior and outright reject packets larger
than 'tx_fifo_depth - 4' with -EINVAL. Add a comment to explain why the
check is necessary. The dev_err() message was removed to avoid cluttering
the dmesg log if an invalid packet is received from userspace.

Fixes: 2ca34b508774 ("staging: axis-fifo: Correct handling of tx_fifo_depth for size validation")
Cc: stable@vger.kernel.org
Signed-off-by: Ovidiu Panait 
Link: https://lore.kernel.org/r/20250817171350.872105-1-ovidiu.panait.oss@gmail.com
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: Correct handling of tx_fifo_depth for size validation

2025-05-18T06:20:36+00:00

commit 2ca34b508774aaa590fc3698a54204706ecca4ba upstream.

Remove erroneous subtraction of 4 from the total FIFO depth read from
device tree. The stored depth is for checking against total capacity,
not initial vacancy. This prevented writes near the FIFO's full size.

The check performed just before data transfer, which uses live reads of
the TDFV register to determine current vacancy, correctly handles the
initial Depth - 4 hardware state and subsequent FIFO fullness.

Fixes: 4a965c5f89de ("staging: add driver for Xilinx AXI-Stream FIFO v4.1 IP core")
Cc: stable@vger.kernel.org
Signed-off-by: Gabriel Shahrouzi 
Link: https://lore.kernel.org/r/20250419012937.674924-1-gshahrouzi@gmail.com
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: Remove hardware resets for user errors

2025-05-18T06:20:36+00:00

commit c6e8d85fafa7193613db37da29c0e8d6e2515b13 upstream.

The axis-fifo driver performs a full hardware reset (via
reset_ip_core()) in several error paths within the read and write
functions. This reset flushes both TX and RX FIFOs and resets the
AXI-Stream links.

Allow the user to handle the error without causing hardware disruption
or data loss in other FIFO paths.

Fixes: 4a965c5f89de ("staging: add driver for Xilinx AXI-Stream FIFO v4.1 IP core")
Cc: stable@vger.kernel.org
Signed-off-by: Gabriel Shahrouzi 
Link: https://lore.kernel.org/r/20250419004306.669605-1-gshahrouzi@gmail.com
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: axis-fifo: Fix function naming in the documentation

2021-05-10T09:19:27+00:00

Fixes the following W=1 kernel build warning(s):

 drivers/staging/axis-fifo/axis-fifo.c:356: warning: expecting prototype for axis_fifo_write(). Prototype was for axis_fifo_read() instead

Cc: Greg Kroah-Hartman 
Cc: Jacob Feder 
Cc: linux-staging@lists.linux.dev
Signed-off-by: Lee Jones 
Link: https://lore.kernel.org/r/20210414181129.1628598-52-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: axis-fifo: Fix some formatting issues

2021-05-10T09:19:26+00:00

Fixes the following W=1 kernel build warning(s):

 drivers/staging/axis-fifo/axis-fifo.c:356: warning: Function parameter or member 'f' not described in 'axis_fifo_read'
 drivers/staging/axis-fifo/axis-fifo.c:356: warning: Function parameter or member 'buf' not described in 'axis_fifo_read'
 drivers/staging/axis-fifo/axis-fifo.c:356: warning: Function parameter or member 'len' not described in 'axis_fifo_read'
 drivers/staging/axis-fifo/axis-fifo.c:356: warning: Function parameter or member 'off' not described in 'axis_fifo_read'
 drivers/staging/axis-fifo/axis-fifo.c:356: warning: expecting prototype for axis_fifo_write(). Prototype was for axis_fifo_read() instead
 drivers/staging/axis-fifo/axis-fifo.c:478: warning: Function parameter or member 'f' not described in 'axis_fifo_write'
 drivers/staging/axis-fifo/axis-fifo.c:478: warning: Function parameter or member 'buf' not described in 'axis_fifo_write'
 drivers/staging/axis-fifo/axis-fifo.c:478: warning: Function parameter or member 'len' not described in 'axis_fifo_write'
 drivers/staging/axis-fifo/axis-fifo.c:478: warning: Function parameter or member 'off' not described in 'axis_fifo_write'

Cc: Greg Kroah-Hartman 
Cc: "John B. Wyatt IV" 
Cc: Jacob Feder 
Cc: linux-staging@lists.linux.dev
Signed-off-by: Lee Jones 
Link: https://lore.kernel.org/r/20210414181129.1628598-37-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: remove redundant dev_err call

2021-04-08T07:24:05+00:00

devm_ioremap_resource() prints error message in itself. Remove the
dev_err call to avoid redundant error message.

Signed-off-by: Muhammad Usama Anjum 
Link: https://lore.kernel.org/r/20210407161202.GA1505056@LEGION
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: Fix parenthesis alignment

2020-04-13T06:55:30+00:00

Fix 2 parenthesis alignment issues.

Reported by checkpatch.

Signed-off-by: John B. Wyatt IV 
Link: https://lore.kernel.org/r/20200402015008.728612-1-jbwyatt4@gmail.com
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: replace spinlock with mutex

2020-01-22T08:58:01+00:00

Following the device's documentation guidance, reading a packet from the
device or writing a packet to it must be atomic. Previously, only
reading device's vacancy (before writing on it) or occupancy (before
reading from it) was locked. Hence, effectively reading the packet or
writing the packet wasn't locked at all. However, reading a packet (and
writing one, to a lesser extent) requires to read 3 different registers
in a specific order, without missing one or else we should reset the
device.

This patch fixes the device's locking mechanism on the FIFO character
device. As the device was using copy_from_user() and copy_to_user(), we
need to replace spinlocks with mutexes.

Signed-off-by: Quentin Deslandes 
Link: https://lore.kernel.org/r/20200121103958.12941-1-quentin.deslandes@itdev.co.uk
Signed-off-by: Greg Kroah-Hartman

staging: axis-fifo: add unspecified HAS_IOMEM dependency

2019-12-17T08:22:11+00:00

Currently CONFIG_XIL_AXIS_FIFO=y implicitly depends on
CONFIG_HAS_IOMEM=y; consequently, on architectures without IOMEM we get
the following build error:

ld: drivers/staging/axis-fifo/axis-fifo.o: in function `axis_fifo_probe':
drivers/staging/axis-fifo/axis-fifo.c:809: undefined reference to `devm_ioremap_resource'

Fix the build error by adding the unspecified dependency.

Reported-by: Brendan Higgins 
Signed-off-by: Brendan Higgins 
Link: https://lore.kernel.org/r/20191211192742.95699-7-brendanhiggins@google.com
Signed-off-by: Greg Kroah-Hartman