Update locking for queue pointers (65b5b0e1) · Commits · Elphel / linux-elphel

src/drivers/ata/ahci_elphel.c

+23 −9

Original line number	Diff line number	Diff line
		@@ -1185,22 +1185,31 @@ static void finish_rec(struct elphel_ahci_priv *dpriv)
		/** Move a pointer to free command slot one step forward. This function holds spin lock #elphel_ahci_priv::flags_lock */
		static int move_tail(struct elphel_ahci_priv *dpriv)
		{
		int ret;
		unsigned long irq_flags;
		size_t slot = (dpriv->tail_ptr + 1) % MAX_CMD_SLOTS;

		spin_lock_irqsave(&dpriv->flags_lock, irq_flags);
		if (slot != dpriv->head_ptr) {
		set_flag(dpriv, LOCK_TAIL);
		dpriv->flags \|= LOCK_TAIL;
		dpriv->tail_ptr = slot;
		dev_dbg(dpriv->dev, "move tail pointer to slot: %u\n", slot);
		return 0;
		ret = 0;
		} else {
		/* no more free command slots */
		return -1;
		ret = -1;
		}
		spin_unlock_irqrestore(&dpriv->flags_lock, irq_flags);

		if (ret == 0)
		dev_dbg(dpriv->dev, "move tail pointer to slot: %u\n", slot);

		return ret;
		}

		/** Move a pointer to next ready command. This function holds spin lock #elphel_ahci_priv::flags_lock*/
		static int move_head(struct elphel_ahci_priv *dpriv)
		{
		int ret;
		size_t use_tail;
		unsigned long irq_flags;
		size_t slot = (dpriv->head_ptr + 1) % MAX_CMD_SLOTS;
		@@ -1212,17 +1221,19 @@ static int move_head(struct elphel_ahci_priv *dpriv)
		} else {
		use_tail = dpriv->tail_ptr;
		}
		spin_unlock_irqrestore(&dpriv->flags_lock, irq_flags);

		if (dpriv->head_ptr != use_tail) {
		dpriv->head_ptr = slot;
		dev_dbg(dpriv->dev, "move head pointer to slot: %u\n", slot);
		return 0;
		ret = 0;
		} else {
		/* no more commands in queue */
		return -1;
		ret = -1;
		}
		spin_unlock_irqrestore(&dpriv->flags_lock, irq_flags);

		if (ret == 0)
		dev_dbg(dpriv->dev, "move head pointer to slot: %u\n", slot);

		return ret;
		}

		/** Check if command queue is empty */
		@@ -1382,6 +1393,7 @@ static ssize_t rawdev_write(struct device *dev, ///< device structure associate
		} else {
		dpriv->flags \|= DELAYED_FINISH;
		}
		dpriv->datascope.reg_stat[CMD_RCVD] = dpriv->datascope.reg_stat[CMD_RCVD] + 1;
		return buff_sz;
		}

		@@ -1440,6 +1452,8 @@ static ssize_t rawdev_write(struct device *dev, ///< device structure associate
		/* new command slot is ready now and can be unlocked */
		reset_flag(dpriv, LOCK_TAIL);

		dpriv->datascope.reg_stat[CMD_RCVD] = dpriv->datascope.reg_stat[CMD_RCVD] + 1;

		if (!proceed) {
		/* disk may be free by the moment, try to grab it */
		spin_lock_irqsave(&dpriv->flags_lock, irq_flags);

src/drivers/ata/ahci_elphel.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -83,7 +83,8 @@ enum {
		REG_PxSERR, ///< value of PxSERR in data buffer
		IRQ_COUNTER, ///< interrupts counter for internal commands
		IRQ_COUNTER_SYS, ///< interrupts counter for system commands
		CMD_SENT ///< number of commands sent
		CMD_SENT, ///< number of commands sent
		CMD_RCVD ///< number of commands received
		};
		struct datascope {
		void __iomem *timestamp_reg; ///< register in vendor specific address range (PxVS) where timestamp can be written

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