Re: [PATCH 03/13] opp: Keep track of currently programmed OPP
From: Ionela Voinescu <hidden>
Date: 2021-07-09 08:57:08
Also in:
linux-arm-kernel, lkml
Hi Viresh, On Thursday 08 Jul 2021 at 13:23:53 (+0530), Viresh Kumar wrote:
On 07-07-21, 11:24, Ionela Voinescu wrote:quoted
Now comes the interesting part: what seems to fix it is a call to clk_get_rate(opp_table->clk) in _set_opp(), which is what basically happened before this patch, as _find_current_opp() was always called. I do not need to do anything with the returned frequency.Wow, thanks for narrowing it down this far :) I had a quick look and this is what I think is the problem here. This platform uses mailbox API to send its frequency change requests to another processor. And the way it is written currently, I don't see any guarantee whatsoever which say "once clk_set_rate() returns, the frequency would have already changed".
I think what was strange to me was that the frequency never seems to change, there isn't just a delay in the new frequency taking effect, as I would expect in these cases. Or if there is a delay, that's quite large - at least a second.
quoted hunk ↗ jump to hunk
And this may exactly be the thing you are able to hit, luckily because of this patchset :) As a quick way of checking if that is right or not, this may make it work:diff --git a/drivers/mailbox/hi3660-mailbox.c b/drivers/mailbox/hi3660-mailbox.c index 395ddc250828..9856c1c84dcf 100644 --- a/drivers/mailbox/hi3660-mailbox.c +++ b/drivers/mailbox/hi3660-mailbox.c@@ -201,6 +201,9 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg) /* Trigger data transferring */ writel(BIT(mchan->ack_irq), base + MBOX_SEND_REG); + + hi3660_mbox_check_state(chan); +
I gave this a try an it does work for me.
return 0; } -------------------------8<------------------------- As a proper fix, something like this (not even compile tested) is required I believe as I don't see the clients would know if the transfer is over. Cc'ing mailbox guys to see what can be done.
I'll give this a try as well when there is consensus. I might even try to review it, if the time allows. Many thanks, Ionela.
quoted hunk ↗ jump to hunk
diff --git a/drivers/clk/hisilicon/clk-hi3660-stub.c b/drivers/clk/hisilicon/clk-hi3660-stub.c index 3a653d54bee0..c1e62ea4cf01 100644 --- a/drivers/clk/hisilicon/clk-hi3660-stub.c +++ b/drivers/clk/hisilicon/clk-hi3660-stub.c@@ -89,7 +89,6 @@ static int hi3660_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate, stub_clk->msg[0], stub_clk->msg[1]); mbox_send_message(stub_clk_chan.mbox, stub_clk->msg); - mbox_client_txdone(stub_clk_chan.mbox, 0); stub_clk->rate = rate; return 0;@@ -131,7 +130,7 @@ static int hi3660_stub_clk_probe(struct platform_device *pdev) /* Use mailbox client without blocking */ stub_clk_chan.cl.dev = dev; stub_clk_chan.cl.tx_done = NULL; - stub_clk_chan.cl.tx_block = false; + stub_clk_chan.cl.tx_block = true; stub_clk_chan.cl.knows_txdone = false; /* Allocate mailbox channel */diff --git a/drivers/mailbox/hi3660-mailbox.c b/drivers/mailbox/hi3660-mailbox.c index 395ddc250828..8f6b787c0aba 100644 --- a/drivers/mailbox/hi3660-mailbox.c +++ b/drivers/mailbox/hi3660-mailbox.c@@ -1,5 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 -// Copyright (c) 2017-2018 HiSilicon Limited. +// Copyright (c) 2017-2018 Hisilicon Limited. // Copyright (c) 2017-2018 Linaro Limited. #include <linux/bitops.h>@@ -83,7 +83,7 @@ static struct hi3660_mbox *to_hi3660_mbox(struct mbox_controller *mbox) return container_of(mbox, struct hi3660_mbox, controller); } -static int hi3660_mbox_check_state(struct mbox_chan *chan) +static bool hi3660_mbox_last_tx_done(struct mbox_chan *chan) { unsigned long ch = (unsigned long)chan->con_priv; struct hi3660_mbox *mbox = to_hi3660_mbox(chan->mbox);@@ -94,20 +94,20 @@ static int hi3660_mbox_check_state(struct mbox_chan *chan) /* Mailbox is ready to use */ if (readl(base + MBOX_MODE_REG) & MBOX_STATE_READY) - return 0; + return true; /* Wait for acknowledge from remote */ ret = readx_poll_timeout_atomic(readl, base + MBOX_MODE_REG, val, (val & MBOX_STATE_ACK), 1000, 300000); if (ret) { dev_err(mbox->dev, "%s: timeout for receiving ack\n", __func__); - return ret; + return false; } /* clear ack state, mailbox will get back to ready state */ writel(BIT(mchan->ack_irq), base + MBOX_ICLR_REG); - return 0; + return true; } static int hi3660_mbox_unlock(struct mbox_chan *chan)@@ -182,10 +182,6 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg) unsigned int i; int ret; - ret = hi3660_mbox_check_state(chan); - if (ret) - return ret; - /* Clear mask for destination interrupt */ writel_relaxed(~BIT(mchan->dst_irq), base + MBOX_IMASK_REG);@@ -207,6 +203,7 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg) static const struct mbox_chan_ops hi3660_mbox_ops = { .startup = hi3660_mbox_startup, .send_data = hi3660_mbox_send_data, + .last_tx_done = hi3660_mbox_last_tx_done, }; static struct mbox_chan *hi3660_mbox_xlate(struct mbox_controller *controller,@@ -259,6 +256,7 @@ static int hi3660_mbox_probe(struct platform_device *pdev) mbox->controller.num_chans = MBOX_CHAN_MAX; mbox->controller.ops = &hi3660_mbox_ops; mbox->controller.of_xlate = hi3660_mbox_xlate; + mbox->controller.txdone_poll = true; /* Initialize mailbox channel data */ chan = mbox->chan;-- viresh