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Input: apple_z2 - fix reading incorrect reports after exiting sleep 

commit d579478cee228bdc0029a0c12a1f6a63ea9d1c77 upstream.

Under certain conditions (more prevalent after a suspend/resume cycle),
the touchscreen controller can send the "boot complete" interrupt before
it actually finished booting. In those cases, attempting to read touch
data resuls in a stream of "not ready" messages being read and
interpreted as a touch report. Check that the response is in fact a
touch report and discard it otherwise.

Reported-by: pitust <piotr@stelmaszek.com>
Closes: https://oftc.catirclogs.org/asahi/2025-12-17#34878715;
Fixes: 471a92f8a2 ("Input: apple_z2 - add a driver for Apple Z2 touchscreens")
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Link: https://patch.msgid.link/20251218-z2-init-fix-v1-1-48e3aa239caf@gmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sasha Finkelstein 2025-12-18 10:15:23 -08:00 committed by Greg Kroah-Hartman
parent 14b1a6009e
commit cae029e057
1 changed files with 4 additions and 0 deletions
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4
drivers/input/touchscreen/apple_z2.c
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@ -21,6 +21,7 @@
#define APPLE_Z2_TOUCH_STARTED 3
#define APPLE_Z2_TOUCH_MOVED 4
#define APPLE_Z2_CMD_READ_INTERRUPT_DATA 0xEB
#define APPLE_Z2_REPLY_INTERRUPT_DATA 0xE1
#define APPLE_Z2_HBPP_CMD_BLOB 0x3001
#define APPLE_Z2_FW_MAGIC 0x5746325A
#define LOAD_COMMAND_INIT_PAYLOAD 0
@ -142,6 +143,9 @@ static int apple_z2_read_packet(struct apple_z2 *z2)
if (error)
return error;
if (z2->rx_buf[0] != APPLE_Z2_REPLY_INTERRUPT_DATA)
return 0;
pkt_len = (get_unaligned_le16(z2->rx_buf + 1) + 8) & 0xfffffffc;
error = spi_read(z2->spidev, z2->rx_buf, pkt_len);