Re: [PATCH net-next v4 02/13] net: wwan: t7xx: Add control DMA interface
flat view
From: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Date: 2022-02-10 13:50:26
Also in:
linux-wireless
On Thu, 13 Jan 2022, Ricardo Martinez wrote:
From: Haijun Liu <haijun.liu@mediatek.com> Cross Layer DMA (CLDMA) Hardware interface (HIF) enables the control path of Host-Modem data transfers. CLDMA HIF layer provides a common interface to the Port Layer. CLDMA manages 8 independent RX/TX physical channels with data flow control in HW queues. CLDMA uses ring buffers of General Packet Descriptors (GPD) for TX/RX. GPDs can represent multiple or single data buffers (DB). CLDMA HIF initializes GPD rings, registers ISR handlers for CLDMA interrupts, and initializes CLDMA HW registers. CLDMA TX flow: 1. Port Layer write 2. Get DB address 3. Configure GPD 4. Triggering processing via HW register write CLDMA RX flow: 1. CLDMA HW sends a RX "done" to host 2. Driver starts thread to safely read GPD 3. DB is sent to Port layer 4. Create a new buffer for GPD ring Signed-off-by: Haijun Liu <haijun.liu@mediatek.com> Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@intel.com> Co-developed-by: Ricardo Martinez <ricardo.martinez@linux.intel.com> Signed-off-by: Ricardo Martinez <ricardo.martinez@linux.intel.com> ---
quoted hunk ↗ jump to hunk
+ struct cldma_ring *tr_ring; + struct cldma_request *tr_done; + struct cldma_request *rx_refill; + struct cldma_request *tx_xmit; + int budget; /* Same as ring buffer size by default */ + spinlock_t ring_lock;
I couldn't figure out what ring_lock is supposed to protect exactly. Since there were tr_ring operations done w/o ring_lock (in t7xx_cldma_gpd_rx_from_q), I was left to wonder whether it's due to a locking bug or me not understanding what ring_lock is supposed to protect. -- i.