Messages in this thread | | | Date | Tue, 12 May 2015 17:28:47 +0200 | From | Noralf Trønnes <> | Subject | Re: [PATCH 2/3 v8] mailbox: Enable BCM2835 mailbox support |
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Den 05.05.2015 22:27, skrev Eric Anholt: > From: Lubomir Rintel <lkundrak@v3.sk> > > 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@v3.sk> > Signed-off-by: Craig McGeachie <slapdau@yahoo.com.au> > Signed-off-by: Eric Anholt <eric@anholt.net> > Cc: Jassi Brar <jassisinghbrar@gmail.com> > Acked-by: Stephen Warren <swarren@wwwdotorg.org> > --- [...] > 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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