linux-kernel - [PATCH v2 0/2] spi: tegra210-quad: Improve timeout handling under high system load

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Message-ID: <20251016132923.3577429-1-va@nvidia.com>
Date: Thu, 16 Oct 2025 13:29:21 +0000
From: Vishwaroop A <va@...dia.com>
To: Mark Brown <broonie@...nel.org>, Thierry Reding
	<thierry.reding@...il.com>, Jonathan Hunter <jonathanh@...dia.com>, "Sowjanya
 Komatineni" <skomatineni@...dia.com>, Laxman Dewangan <ldewangan@...dia.com>,
	<smangipudi@...dia.com>, <kyarlagadda@...dia.com>
CC: Vishwaroop A <va@...dia.com>, <linux-spi@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 0/2] spi: tegra210-quad: Improve timeout handling under high system load

Hi,

This patch series addresses timeout handling issues in the Tegra QSPI driver
that occur under high system load conditions. We've observed that when CPUs
are saturated (due to error injection, RAS firmware activity, or general CPU
contention), QSPI interrupt handlers can be delayed, causing spurious transfer
failures even though the hardware completed the operation successfully.

Patch 1 fixes a stale pointer issue by ensuring curr_xfer is cleared on timeout
and checked when the IRQ thread finally runs. It also ensures interrupts are
properly cleared on failure paths.

Patch 2 adds hardware status checking on timeout. Before failing a transfer,
the driver now reads QSPI_TRANS_STATUS to verify if the hardware actually
completed the operation. If so, it manually invokes the completion handler
instead of failing the transfer. This distinguishes genuine hardware timeouts
from delayed/lost interrupts.

These changes have been tested in production environments under various high
load scenarios including RAS testing and CPU saturation workloads.

Changes in v2:
- Fixed indentation in patch 1/2: The "Reset controller if timeout happens"
  block now has correct indentation (inside the WARN_ON_ONCE block)
- No functional changes

Testing:
- Verified normal operation under light load
- Tested under heavy CPU load with concurrent workloads
- Validated with RAS firmware activity and error injection
- Confirmed no regressions in existing timeout behavior

Thierry Reding (1):
  spi: tegra210-quad: Fix timeout handling

Vishwaroop A (1):
  spi: tegra210-quad: Check hardware status on timeout

 drivers/spi/spi-tegra210-quad.c | 195 ++++++++++++++++++++++++++------
 1 file changed, 138 insertions(+), 57 deletions(-)

-- 
2.34.1