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net: ipa: do not cache channel state
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It is possible for a GSI channel's state to be changed as a result
of an action by a different execution environment.  Specifically,
the modem is able to issue a GSI generic command that causes a state
change on a GSI channel associated with the AP.

A channel's state only needs to be known when a channel is allocated
or deallocaed, started or stopped, or reset.  So there is little
value in caching the state anyway.

Stop recording a copy of the channel's last known state, and instead
fetch the true state from hardware whenever it's needed.  In such
cases, *do* record the state in a local variable, in case an error
message reports it (so the value reported is the value seen).

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Alex Elder authored and David S. Miller committed May 1, 2020
1 parent aba7924 commit a2003b3
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Showing 2 changed files with 55 additions and 35 deletions.
87 changes: 54 additions & 33 deletions drivers/net/ipa/gsi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -415,7 +415,7 @@ static void gsi_evt_ring_de_alloc_command(struct gsi *gsi, u32 evt_ring_id)
evt_ring->state);
}

/* Return the hardware's notion of the current state of a channel */
/* Fetch the current state of a channel from hardware */
static enum gsi_channel_state gsi_channel_state(struct gsi_channel *channel)
{
u32 channel_id = gsi_channel_id(channel);
Expand All @@ -433,16 +433,18 @@ gsi_channel_command(struct gsi_channel *channel, enum gsi_ch_cmd_opcode opcode)
{
struct completion *completion = &channel->completion;
u32 channel_id = gsi_channel_id(channel);
struct gsi *gsi = channel->gsi;
u32 val;

val = u32_encode_bits(channel_id, CH_CHID_FMASK);
val |= u32_encode_bits(opcode, CH_OPCODE_FMASK);

if (gsi_command(channel->gsi, GSI_CH_CMD_OFFSET, val, completion))
if (gsi_command(gsi, GSI_CH_CMD_OFFSET, val, completion))
return 0; /* Success! */

dev_err(channel->gsi->dev, "GSI command %u to channel %u timed out "
"(state is %u)\n", opcode, channel_id, channel->state);
dev_err(gsi->dev,
"GSI command %u to channel %u timed out (state is %u)\n",
opcode, channel_id, gsi_channel_state(channel));

return -ETIMEDOUT;
}
Expand All @@ -451,18 +453,21 @@ gsi_channel_command(struct gsi_channel *channel, enum gsi_ch_cmd_opcode opcode)
static int gsi_channel_alloc_command(struct gsi *gsi, u32 channel_id)
{
struct gsi_channel *channel = &gsi->channel[channel_id];
enum gsi_channel_state state;
int ret;

/* Get initial channel state */
channel->state = gsi_channel_state(channel);

if (channel->state != GSI_CHANNEL_STATE_NOT_ALLOCATED)
state = gsi_channel_state(channel);
if (state != GSI_CHANNEL_STATE_NOT_ALLOCATED)
return -EINVAL;

ret = gsi_channel_command(channel, GSI_CH_ALLOCATE);
if (!ret && channel->state != GSI_CHANNEL_STATE_ALLOCATED) {

/* Channel state will normally have been updated */
state = gsi_channel_state(channel);
if (!ret && state != GSI_CHANNEL_STATE_ALLOCATED) {
dev_err(gsi->dev, "bad channel state (%u) after alloc\n",
channel->state);
state);
ret = -EIO;
}

Expand All @@ -472,18 +477,21 @@ static int gsi_channel_alloc_command(struct gsi *gsi, u32 channel_id)
/* Start an ALLOCATED channel */
static int gsi_channel_start_command(struct gsi_channel *channel)
{
enum gsi_channel_state state = channel->state;
enum gsi_channel_state state;
int ret;

state = gsi_channel_state(channel);
if (state != GSI_CHANNEL_STATE_ALLOCATED &&
state != GSI_CHANNEL_STATE_STOPPED)
return -EINVAL;

ret = gsi_channel_command(channel, GSI_CH_START);
if (!ret && channel->state != GSI_CHANNEL_STATE_STARTED) {

/* Channel state will normally have been updated */
state = gsi_channel_state(channel);
if (!ret && state != GSI_CHANNEL_STATE_STARTED) {
dev_err(channel->gsi->dev,
"bad channel state (%u) after start\n",
channel->state);
"bad channel state (%u) after start\n", state);
ret = -EIO;
}

Expand All @@ -493,65 +501,77 @@ static int gsi_channel_start_command(struct gsi_channel *channel)
/* Stop a GSI channel in STARTED state */
static int gsi_channel_stop_command(struct gsi_channel *channel)
{
enum gsi_channel_state state = channel->state;
enum gsi_channel_state state;
int ret;

state = gsi_channel_state(channel);
if (state != GSI_CHANNEL_STATE_STARTED &&
state != GSI_CHANNEL_STATE_STOP_IN_PROC)
return -EINVAL;

ret = gsi_channel_command(channel, GSI_CH_STOP);
if (ret || channel->state == GSI_CHANNEL_STATE_STOPPED)

/* Channel state will normally have been updated */
state = gsi_channel_state(channel);
if (ret || state == GSI_CHANNEL_STATE_STOPPED)
return ret;

/* We may have to try again if stop is in progress */
if (channel->state == GSI_CHANNEL_STATE_STOP_IN_PROC)
if (state == GSI_CHANNEL_STATE_STOP_IN_PROC)
return -EAGAIN;

dev_err(channel->gsi->dev, "bad channel state (%u) after stop\n",
channel->state);
dev_err(channel->gsi->dev,
"bad channel state (%u) after stop\n", state);

return -EIO;
}

/* Reset a GSI channel in ALLOCATED or ERROR state. */
static void gsi_channel_reset_command(struct gsi_channel *channel)
{
enum gsi_channel_state state;
int ret;

msleep(1); /* A short delay is required before a RESET command */

if (channel->state != GSI_CHANNEL_STATE_STOPPED &&
channel->state != GSI_CHANNEL_STATE_ERROR) {
state = gsi_channel_state(channel);
if (state != GSI_CHANNEL_STATE_STOPPED &&
state != GSI_CHANNEL_STATE_ERROR) {
dev_err(channel->gsi->dev,
"bad channel state (%u) before reset\n",
channel->state);
"bad channel state (%u) before reset\n", state);
return;
}

ret = gsi_channel_command(channel, GSI_CH_RESET);
if (!ret && channel->state != GSI_CHANNEL_STATE_ALLOCATED)

/* Channel state will normally have been updated */
state = gsi_channel_state(channel);
if (!ret && state != GSI_CHANNEL_STATE_ALLOCATED)
dev_err(channel->gsi->dev,
"bad channel state (%u) after reset\n",
channel->state);
"bad channel state (%u) after reset\n", state);
}

/* Deallocate an ALLOCATED GSI channel */
static void gsi_channel_de_alloc_command(struct gsi *gsi, u32 channel_id)
{
struct gsi_channel *channel = &gsi->channel[channel_id];
enum gsi_channel_state state;
int ret;

if (channel->state != GSI_CHANNEL_STATE_ALLOCATED) {
dev_err(gsi->dev, "bad channel state (%u) before dealloc\n",
channel->state);
state = gsi_channel_state(channel);
if (state != GSI_CHANNEL_STATE_ALLOCATED) {
dev_err(gsi->dev,
"bad channel state (%u) before dealloc\n", state);
return;
}

ret = gsi_channel_command(channel, GSI_CH_DE_ALLOC);
if (!ret && channel->state != GSI_CHANNEL_STATE_NOT_ALLOCATED)
dev_err(gsi->dev, "bad channel state (%u) after dealloc\n",
channel->state);

/* Channel state will normally have been updated */
state = gsi_channel_state(channel);
if (!ret && state != GSI_CHANNEL_STATE_NOT_ALLOCATED)
dev_err(gsi->dev,
"bad channel state (%u) after dealloc\n", state);
}

/* Ring an event ring doorbell, reporting the last entry processed by the AP.
Expand Down Expand Up @@ -778,6 +798,7 @@ int gsi_channel_start(struct gsi *gsi, u32 channel_id)
int gsi_channel_stop(struct gsi *gsi, u32 channel_id)
{
struct gsi_channel *channel = &gsi->channel[channel_id];
enum gsi_channel_state state;
u32 retries;
int ret;

Expand All @@ -787,7 +808,8 @@ int gsi_channel_stop(struct gsi *gsi, u32 channel_id)
* STOP command timed out. We won't stop a channel if stopping it
* was successful previously (so we still want the freeze above).
*/
if (channel->state == GSI_CHANNEL_STATE_STOPPED)
state = gsi_channel_state(channel);
if (state == GSI_CHANNEL_STATE_STOPPED)
return 0;

/* RX channels might require a little time to enter STOPPED state */
Expand Down Expand Up @@ -941,7 +963,6 @@ static void gsi_isr_chan_ctrl(struct gsi *gsi)
channel_mask ^= BIT(channel_id);

channel = &gsi->channel[channel_id];
channel->state = gsi_channel_state(channel);

complete(&channel->completion);
}
Expand Down
3 changes: 1 addition & 2 deletions drivers/net/ipa/gsi.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -113,8 +113,7 @@ struct gsi_channel {
u16 tre_count;
u16 event_count;

struct completion completion; /* signals channel state changes */
enum gsi_channel_state state;
struct completion completion; /* signals channel command completion */

struct gsi_ring tre_ring;
u32 evt_ring_id;
Expand Down

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