Den 05.05.2015 22:27, skrev Eric Anholt:
From: Lubomir Rintel <lkundrak@xxxxx>
This mailbox driver provides a single mailbox channel to write 32-bit
values to the VPU and get a 32-bit response. The Raspberry Pi
firmware uses this mailbox channel to implement firmware calls, while
Roku 2 (despite being derived from the same firmware tree) doesn't.
The driver was originally submitted by Lubomir, based on the
out-of-tree 2708 mailbox driver. Eric Anholt fixed it up for
upstreaming, with the major functional change being that it now has no
notion of multiple channels (since that is a firmware-dependent
concept) and instead the raspberrypi-firmware driver will do that
bit-twiddling in its own messages.
Signed-off-by: Lubomir Rintel <lkundrak@xxxxx>
Signed-off-by: Craig McGeachie <slapdau@xxxxxxxxxxxx>
Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
Cc: Jassi Brar <jassisinghbrar@xxxxxxxxx>
Acked-by: Stephen Warren <swarren@xxxxxxxxxxxxx>
---
[...]
diff --git a/drivers/mailbox/bcm2835-mailbox.c b/drivers/mailbox/bcm2835-mailbox.c
[...]
+static bool bcm2835_last_tx_done(struct mbox_chan *link)
+{
+ struct bcm2835_mbox *mbox = bcm2835_link_mbox(link);
+ bool ret;
+
+ spin_lock(&mbox->lock);
+ ret = !(readl(mbox->regs + MAIL0_STA) & ARM_MS_FULL);
I don't know how the mailbox framework uses this function,
but MAIL0_STA might be wrong here.
Phil Elwell detected a bug in the downstream mailbox driver in
the mbox_write function where it waits for space to be available
in the FIFO. His observation:
With the VC reader blocked and the ARM writing, MAIL0_STA reads
empty permanently while MAIL1_STA goes from empty (0x40000000)
to non-empty (0x00000001-0x00000007) to full (0x80000008).
See:
https://github.com/raspberrypi/linux/commit/3018d8a0996ad2340ba1b3f473f705ef285b01b5
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