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[61.228.48.72]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84c2af31790sm2088157b3a.37.2026.07.17.20.22.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Jul 2026 20:22:47 -0700 (PDT) From: Shih-Yuan Lee To: Mark Brown Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, Shih-Yuan Lee Subject: [PATCH v8 0/2] spi: pxa2xx: MacBook8,1 quirk and LPSS S3 resume state fixes Date: Sat, 18 Jul 2026 11:22:37 +0800 Message-Id: <20260718032239.19136-1-fourdollars@debian.org> X-Mailer: git-send-email 2.39.5 Precedence: bulk X-Mailing-List: linux-spi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Mark, This patch series resolves two issues in the spi-pxa2xx host controller driver related to Intel LPSS SPI controllers. Patch 1 moves the forced PIO mode quirk for the Apple MacBook8,1 LPSS SPI controller from the client driver (applespi) to the host controller PCI glue driver (spi-pxa2xx-pci) where it belongs. It also fixes a runtime PM issue: when DMA is disabled, aggressive runtime clock gating causes PCIe Completion Timeouts on subsequent MMIO accesses. Patch 2 fixes S3 suspend/resume for Intel LPSS SPI controllers. The LPSS power domain is fully removed across S3, losing all private register state. Accessing MMIO on resume while the block is held in reset causes a PCIe Completion Timeout and a watchdog system reset. To fix this, we save the LPSS private registers in struct driver_data during suspend, de-assert resets first on resume, and restore the saved registers. Changes in v8: - Addressed feedback from Sashiko review on the v7 patchset: - Fixed runtime PM resume interrupt storm in ssp_int() by checking drv_data->clk_enabled instead of pm_runtime_get_if_active() == 0. - Fixed PM disabled configuration (CONFIG_PM=n) support in ssp_int() by avoiding active <= 0 early returns. - Reordered suspend and remove sequences to invoke pxa_ssp_disable() before setting drv_data->suspended = true and synchronizing the IRQ, closing a race window where level-triggered interrupts could cause a storm. - Masked hardware interrupt generation in pxa2xx_spi_runtime_suspend() via pxa_ssp_disable() to prevent unexpected interrupts during clock enable. - Avoided PCIe Completion Timeout system hangs on newer LPSS platforms (SPT, BXT, CNL) by introducing pxa2xx_spi_need_lpss_restore() to restrict MMIO save/restore loops to LPT, BYT, and BSW platforms (which lack an MFD parent). - Fixed compiler error in pxa2xx_spi_probe() due to unused label. Changes in v7: - Addressed feedback from Sashiko review on the v6 patchset: - Fixed a race condition during probe by moving the request_irq() call after the clock is enabled and the suspended flag is cleared. This prevents an early shared interrupt from asserting and triggering an interrupt storm before the clock is active to allow clearing it. - Rectified the teardown sequence in pxa2xx_spi_remove(): first set drv_data->suspended to true and disable SSP hardware-level interrupt generation (pxa_ssp_disable()), then call synchronize_irq() to wait for in-flight interrupt handlers to complete, free the IRQ, and only then disable the clocks. This eliminates both post-clock-disable MMIO accesses and unhandled shared hardware interrupt storms. - Clarified that the unconditional MMIO register access in pxa2xx_spi_suspend() is safe because pm_runtime_resume_and_get() is invoked at the very beginning of the suspend callback, guaranteeing the LPSS device is active and clocked during register disabling/saving. - Added spi_controller_resume() recovery to the error path of spi_controller_suspend() in pxa2xx_spi_suspend() to prevent the controller from remaining permanently disabled in the event system suspend is aborted. Changes in v6: - Addressed feedback from Sashiko review on the v5 patchset: - Added a synchronize_irq() call to the spi_controller_resume() error path in pxa2xx_spi_resume(). This ensures any concurrent shared interrupt handlers (which might execute because drv_data->suspended = false was set earlier) finish executing before we disable the clock, preventing PCIe timeouts. - Checked and confirmed that active == 0 is the correct check in ssp_int(). If Runtime PM is disabled, pm_runtime_get_if_active() returns a negative error code (like -EINVAL). Changing this check to active <= 0 would cause a regression on non-PM configurations because the handler would always return IRQ_NONE. Under disabled Runtime PM, the hardware clock is kept constantly active, so it is safe to proceed and read registers when active < 0. Changes in v5: - Reverted runtime PM configuration in spi-pxa2xx-pci.c to be unconditional. This prevents the usage count from leaking by +1 on unbind for PIO mode, while letting pxa2xx_spi_probe()'s pm_runtime_get_noresume() and pxa2xx_spi_remove()'s pm_runtime_put_noidle() handle the permanent autosuspend lockout for PIO devices symmetrically. - Removed the pm_runtime_forbid() call from pxa2xx_spi_remove(). This resolves reference leaks for non-PCI platform devices where pm_runtime_allow() was never called during probe. - Delayed clearing the drv_data->suspended flag on resume until after LPSS reset deassertion and private register restoration are complete. This prevents a shared interrupt from firing during resume and attempting to read the SSSR register while the LPSS block is still held in reset. - Set drv_data->suspended = true on spi_controller_resume() failure path in pxa2xx_spi_resume(). This ensures that subsequent shared interrupts do not attempt register access once the clock is disabled. Changes in v4: - Track clock state using drv_data->clk_enabled via pxa2xx_spi_clk_enable() and pxa2xx_spi_clk_disable() helper functions. This guarantees clock enable/disable symmetry, preventing clock disable count underflows and framework warnings on S3 resume or runtime autosuspend error paths. - Introduce drv_data->suspended flag to protect MMIO access in ssp_int() during system suspend and runtime suspend transition windows. - Initialize drv_data->suspended = true early in probe(), clearing it only after the clock is successfully enabled. This completely prevents shared interrupt handler races during device probe when the clock is still off. - Call synchronize_irq() after setting drv_data->suspended = true in suspend and runtime_suspend. This ensures any running shared interrupt handlers finish executing before the clock is physically turned off. Changes in v3: - Avoid PM reference leaks on probe bind/unbind cycle by keeping probe PM configuration symmetric. - Prevent userspace (PowerTOP, udev) from overriding runtime PM settings when DMA is disabled by holding a PM reference via pm_runtime_get_noresume() in pxa2xx_spi_probe() and dropping it in remove/error paths. - Check device status in the shared interrupt handler ssp_int() using pm_runtime_get_if_active() instead of pm_runtime_suspended(). If the device is suspending (RPM_SUSPENDING) or suspended, ssp_int() immediately returns IRQ_NONE to avoid reading unclocked MMIO registers during power transition. - Adjust the driver teardown order in pxa2xx_spi_remove() and probe error paths: always call free_irq() to unregister the handler before calling clk_disable_unprepare() to turn off the clock, preventing concurrent interrupts from reading registers while the clock is disabled. - On S3 suspend success path, return 0 directly without dropping the PM reference. This preserves the acquired PM reference across suspend. On S3 resume, release it via pm_runtime_put_autosuspend(), and ensure all error paths in resume (clock enable failure or spi_controller_resume failure) jump to out_put to correctly release the reference, preventing reference count underflow and leaks. - Avoid duplicate can-DMA pci_info() logging by checking the pre-computed enable_dma status in probe and passing a verbose flag to can_dma(). Changes in v2: - Addressed feedback from Mark Brown on the original v1 series. - Used drv_data->lpss_base together with relative offsets rather than hardcoding absolute MMIO offsets that vary between LPSS IP revisions. - Moved the register save block in suspend to after the controller is quiesced (after spi_controller_suspend() and pxa_ssp_disable()). - Store the context array lpss_priv_ctx[6] inside struct driver_data instead of struct pxa2xx_spi_controller. This keeps the changes entirely local to the core driver, preventing symbol version mismatches (disagrees about version of symbol) for other subsystem components (e.g., spi-pxa2xx-platform.ko). - Restrict the save/restore loop to the first 6 LPSS private registers (offsets 0x00 to 0x14). Offsets beyond 0x14 (except CS control at 0x18, which is re-initialised by lpss_ssp_setup()) are reserved/unimplemented on LPT platforms (such as MacBook8,1), and writing to them triggers a PCIe Completion Timeout causing a system freeze. - Added named constants for LPSS_PRIV_RESETS and the de-assert value. - Wrapped S3 suspend/resume with pm_runtime_resume_and_get() and pm_runtime_put_autosuspend() respectively. Link: https://bugzilla.kernel.org/show_bug.cgi?id=108331 Shih-Yuan Lee (2): spi: pxa2xx: disable DMA and fix runtime PM for Apple MacBook8,1 spi: pxa2xx: restore LPSS private register state on S3 resume drivers/spi/spi-pxa2xx-pci.c | 37 +++++- drivers/spi/spi-pxa2xx.c | 238 +++++++++++++++++++++++++++++------ drivers/spi/spi-pxa2xx.h | 4 + 3 files changed, 238 insertions(+), 41 deletions(-) -- 2.39.5