kernel/git/next/linux-next.git/drivers/mailbox/pcc.c, branch stable

mailbox: pcc: Fix command timeout due to missed interrupt

2026-08-15T20:41:12+00:00

PCC command execution can time out when a fast platform completes a transaction and signals the platform interrupt before pcc_send_data() marks the channel as in use. For shared platform interrupts, the type 3 handler uses chan_in_use to decide whether the interrupt belongs to the channel. If it observes false, it ignores the completion and the caller waits until timeout. Publish chan_in_use before ringing the doorbell. Use WRITE_ONCE() for the lockless flag updates and READ_ONCE() in the interrupt handler. The following ordered I/O accessor orders the flag store before the platform is notified. Clear chan_in_use if ringing the doorbell fails. Otherwise, leave it set until the interrupt handler completes the transaction, clearing it before the mailbox core can submit another transfer. Fixes: 3db174e478cb ("mailbox: pcc: Support shared interrupt for multiple subspaces") Signed-off-by: Huisong Li Signed-off-by: Sudeep Holla Tested-by: Adam Young Signed-off-by: Jassi Brar

mailbox: pcc: Check shared memory signature on request

2026-08-15T20:41:12+00:00

ACPI 6.6 Tables 14.9 and 14.12 define the PCC shared memory signature as the bitwise OR of 0x50434300 and the PCC subspace ID. They also clarify that the signature is populated by the platform and verified by OSPM. The signature is at byte offset 0 in the generic, extended and reduced PCC shared memory layouts. Check the signature when a client requests a PCC mailbox channel, after mapping shared memory and before binding the mailbox client. This keeps the check in the PCC mailbox controller instead of duplicating it in individual clients. Treat a signature mismatch as a warning rather than rejecting the channel request. Making this newly added check fatal could break existing systems whose firmware did not populate the signature correctly even though PCC communication works. Continue to reject shared memory that is too small to contain a signature because it cannot be inspected safely. Cc: Huisong Li Signed-off-by: Sudeep Holla Tested_by: Adam Young Signed-off-by: Jassi Brar

mailbox: pcc: Notify clients on polled completion

2026-08-15T20:41:12+00:00

PCC channels without a platform interrupt rely on the mailbox polling path to detect command completion. That path currently only reports transmit completion to the mailbox core, so clients that wait for their receive callback do not get notified when the command completes. Call mbox_chan_received_data() when polling observes completion on a channel without a platform IRQ, matching the interrupt-driven completion path. Reported-by: Cristian Marussi Acked-by: Huisong Li Signed-off-by: Sudeep Holla Reviewed-by: Adam Young Signed-off-by: Jassi Brar

mailbox: remove superfluous internal header

2026-03-29T16:07:26+00:00

Quite some controller drivers use the defines from the internal header already. This prevents controller drivers outside the mailbox directory. Move the defines to the public controller header to allow this again as the defines are not strictly internal anyhow. Signed-off-by: Wolfram Sang Reviewed-by: Sudeep Holla Reviewed-by: Daniel Baluta Signed-off-by: Jassi Brar

mailbox: pcc: Remove spurious IRQF_ONESHOT usage

2026-01-25T00:42:33+00:00

The PCC code currently specifies IRQF_ONESHOT if the interrupt could potentially be shared but doesn't actually use request_threaded_irq() and the interrupt handler does not use IRQ_WAKE_THREAD so IRQF_ONESHOT is never relevant. Since commit aef30c8d569c ("genirq: Warn about using IRQF_ONESHOT without a threaded handler") specifying it has resulted in a WARN_ON(), fix this by removing IRQF_ONESHOT. Reported-by: Aishwarya TCV Signed-off-by: Mark Brown Reviewed-by: Sudeep Holla Signed-off-by: Jassi Brar

mailbox: pcc: Clear any pending responder interrupts before enabling it

2026-01-18T20:19:21+00:00

Some platforms may leave a responder interrupt pending from earlier transactions. If a PCC responder channel has a pending interrupt when the controller starts up, enabling the IRQ line without first clearing the condition can lead to a spurious interrupt which could disrupt other transmissions if the IRQ is shared. Explicitly clear any pending responder interrupt before enabling the IRQ to ensure a clean start. Acknowledge the responder channel via pcc_chan_acknowledge() in startup before requesting/enablement of the IRQ. This ensures a clean baseline for the first transfer/receiption of the notification/response. Signed-off-by: Sudeep Holla Tested-by: Adam Young Signed-off-by: Jassi Brar

mailbox: pcc: Initialize SHMEM before binding the channel with the client

2026-01-18T20:19:21+00:00

The PCC channel's shared memory region must be set up before the mailbox controller binds the channel with the client, as the binding process may trigger client operations like startup() that may rely on SHMEM being initialized. Reorder the setup sequence to ensure the shared memory is ready before binding. Initialize and map the PCC shared memory (SHMEM) prior to calling mbox_bind_client() so that clients never observe an uninitialized or NULL SHMEM during bind-time callbacks or early use in startup(). This makes the PCC mailbox channel bring-up order consistent and eliminates a race between SHMEM setup and client binding. This will be needed in channel startup to clear/acknowledge any pending interrupts before enabling them. Signed-off-by: Sudeep Holla Acked-by: lihuisong@huawei.com Tested-by: Adam Young Signed-off-by: Jassi Brar

mailbox: pcc: Mark Tx as complete in PCC IRQ handler

2026-01-18T20:19:20+00:00

The PCC IRQ handler clears channel-in-use and notifies clients with mbox_chan_received_data(), but it does not explicitly mark the transmit as complete. In IRQ completion mode this could leave Tx complete waiters hanging or lead to generic timeouts in the mailbox core. Invoke mbox_chan_txdone() in the IRQ path once the platform has acknowledged the transfer so the core can wake any waiters and update state accordingly. Signed-off-by: Sudeep Holla Tested-by: Adam Young Signed-off-by: Jassi Brar

mailbox: pcc: Set txdone_irq/txdone_poll based on PCCT flags

2026-01-18T20:19:20+00:00

The PCC controller currently enables txdone via IRQ if the PCCT exposes platform capability to generate command completion interrupt, but it leaves txdone_poll unchanged. Make the behaviour explicit: - If ACPI_PCCT_DOORBELL is present, use txdone_irq and disable polling. - Otherwise, disable txdone_irq and fall back to txdone_poll. Configure the PCC mailbox to use interrupt-based completion for PCC types that signal completion via IRQ using TXDONE_BY_IRQ, and fall back to polling for others using TXDONE_BY_POLL. This ensures the PCC driver uses the appropriate completion mechanism according to the PCCT table definition and makes the completion mode unambiguous avoiding mixed signalling when the platform lacks a doorbell flag set. Signed-off-by: Sudeep Holla Tested-by: Adam Young Signed-off-by: Jassi Brar

mailbox: pcc: Wire up ->last_tx_done() for PCC channels

2026-01-18T20:19:20+00:00

Some PCC users poll for completion between transfers and benefit from the knowledge of previous Tx completion check through the mailbox framework's ->last_tx_done() op. Hook up the last_tx_done callback in the PCC mailbox driver so the mailbox framework can correctly query the completion status of the last transmitted message. This aligns PCC with other controllers that already implement such last_tx_done status query. No functional change unless callers use ->last_tx_done(). Normal Tx and IRQ paths are unchanged. This change just improves synchronization and avoids unnecessary timeouts for non-interrupt driven channels by ensuring correct completion detection for PCC channels that don’t rely on interrupts. Signed-off-by: Sudeep Holla Tested-by: Adam Young Signed-off-by: Jassi Brar