As reported by Aaro, the JZ4740 MMC driver throws a warning
when the kernel is built without preemption (CONFIG_PREEMPT_NONE=y).
[ 16.461094] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 567 host->next_data.cookie 568
[ 16.473120] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 568 host->next_data.cookie 569
[ 16.485144] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 569 host->next_data.cookie 570
[ 16.497170] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 570 host->next_data.cookie 571
[ 16.509194] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 571 host->next_data.cookie 572
[ 16.532421] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 572 host->next_data.cookie 573
[ 16.544594] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 573 host->next_data.cookie 574
[ 16.556621] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 574 host->next_data.cookie 575
[ 16.568638] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 575 host->next_data.cookie 576
[ 16.601092] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 582 host->next_data.cookie 583
The problem seems to be related to how pre_req/post_req is implemented.
Currently, it seems the driver expects jz4740_mmc_prepare_dma_data()
to be called with monotonically increasing host_cookie values,
which is wrong.
Moreover, the implementation is overly complicated, keeping track
of unneeded "next cookie" state.
So, instead of attempting to fix the current pre_req/post_req
implementation, this commit refactors the driver, dropping
the state, following other drivers such as dw_mmc and sdhci.
Cc: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
Cc: Mathieu Malaterre <malat@xxxxxxxxxx>
Reported-by: Aaro Koskinen <aaro.koskinen@xxxxxx>
Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
---
drivers/mmc/host/jz4740_mmc.c | 118 ++++++++++++++++------------------
1 file changed, 54 insertions(+), 64 deletions(-)
diff --git a/drivers/mmc/host/jz4740_mmc.c b/drivers/mmc/host/jz4740_mmc.c
index 0c1efd5100b7..ca20e2f81be8 100644
--- a/drivers/mmc/host/jz4740_mmc.c
+++ b/drivers/mmc/host/jz4740_mmc.c
@@ -126,9 +126,23 @@ enum jz4740_mmc_state {
JZ4740_MMC_STATE_DONE,
};
-struct jz4740_mmc_host_next {
- int sg_len;
- s32 cookie;
+/*
+ * The MMC core allows to prepare a mmc_request while another mmc_request
+ * is in-flight. This is used via the pre_req/post_req hooks.
+ * This driver uses the pre_req/post_req hooks to map/unmap the mmc_request.
+ * Following what other drivers do (sdhci, dw_mmc) we use the following cookie
+ * flags to keep track of the mmc_request mapping state.
+ *
+ * COOKIE_UNMAPPED: the request is not mapped.
+ * COOKIE_PREMAPPED: the request was mapped in pre_req,
+ * and should be unmapped in post_req.
+ * COOKIE_MAPPED: the request was mapped in the irq handler,
+ * and should be unmapped before mmc_request_done is called..
+ */
+enum jz4780_cookie {
+ COOKIE_UNMAPPED = 0,
+ COOKIE_PREMAPPED,
+ COOKIE_MAPPED,
};
struct jz4740_mmc_host {
@@ -162,9 +176,7 @@ struct jz4740_mmc_host {
/* DMA support */
struct dma_chan *dma_rx;
struct dma_chan *dma_tx;
- struct jz4740_mmc_host_next next_data;
bool use_dma;
- int sg_len;
/* The DMA trigger level is 8 words, that is to say, the DMA read
* trigger is when data words in MSC_RXFIFO is >= 8 and the DMA write
@@ -226,9 +238,6 @@ static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host *host)
return PTR_ERR(host->dma_rx);
}
- /* Initialize DMA pre request cookie */
- host->next_data.cookie = 1;
-
return 0;
}
@@ -245,60 +254,44 @@ static void jz4740_mmc_dma_unmap(struct jz4740_mmc_host *host,
enum dma_data_direction dir = mmc_get_dma_dir(data);
dma_unmap_sg(chan->device->dev, data->sg, data->sg_len, dir);
+ data->host_cookie = COOKIE_UNMAPPED;
}
-/* Prepares DMA data for current/next transfer, returns non-zero on failure */
+/* Prepares DMA data for current or next transfer.
+ * A request can be in-flight when this is called.
+ */
static int jz4740_mmc_prepare_dma_data(struct jz4740_mmc_host *host,
struct mmc_data *data,
- struct jz4740_mmc_host_next *next,
- struct dma_chan *chan)
+ int cookie)
{
- struct jz4740_mmc_host_next *next_data = &host->next_data;
+ struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
enum dma_data_direction dir = mmc_get_dma_dir(data);
- int sg_len;
-
- if (!next && data->host_cookie &&
- data->host_cookie != host->next_data.cookie) {
- dev_warn(mmc_dev(host->mmc),
- "[%s] invalid cookie: data->host_cookie %d host->next_data.cookie %d\n",
- __func__,
- data->host_cookie,
- host->next_data.cookie);
- data->host_cookie = 0;
- }
+ int sg_count;
- /* Check if next job is already prepared */
- if (next || data->host_cookie != host->next_data.cookie) {
- sg_len = dma_map_sg(chan->device->dev,
- data->sg,
- data->sg_len,
- dir);
+ if (data->host_cookie == COOKIE_PREMAPPED)
+ return data->sg_count;
- } else {
- sg_len = next_data->sg_len;
- next_data->sg_len = 0;
- }
+ sg_count = dma_map_sg(chan->device->dev,
+ data->sg,
+ data->sg_len,
+ dir);
- if (sg_len <= 0) {
+ if (sg_count <= 0) {
dev_err(mmc_dev(host->mmc),
"Failed to map scatterlist for DMA operation\n");
return -EINVAL;
}
- if (next) {
- next->sg_len = sg_len;
- data->host_cookie = ++next->cookie < 0 ? 1 : next->cookie;
- } else
- host->sg_len = sg_len;
+ data->sg_count = sg_count;
+ data->host_cookie = cookie;
- return 0;
+ return data->sg_count;
}
static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
struct mmc_data *data)
{
- int ret;
- struct dma_chan *chan;
+ struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
struct dma_async_tx_descriptor *desc;
struct dma_slave_config conf = {
.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
@@ -306,29 +299,26 @@ static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
.src_maxburst = JZ4740_MMC_FIFO_HALF_SIZE,
.dst_maxburst = JZ4740_MMC_FIFO_HALF_SIZE,
};
+ int sg_count;
if (data->flags & MMC_DATA_WRITE) {
conf.direction = DMA_MEM_TO_DEV;
conf.dst_addr = host->mem_res->start + JZ_REG_MMC_TXFIFO;
conf.slave_id = JZ4740_DMA_TYPE_MMC_TRANSMIT;
- chan = host->dma_tx;
} else {
conf.direction = DMA_DEV_TO_MEM;
conf.src_addr = host->mem_res->start + JZ_REG_MMC_RXFIFO;
conf.slave_id = JZ4740_DMA_TYPE_MMC_RECEIVE;
- chan = host->dma_rx;
}
- ret = jz4740_mmc_prepare_dma_data(host, data, NULL, chan);
- if (ret)
- return ret;
+ sg_count = jz4740_mmc_prepare_dma_data(host, data, COOKIE_MAPPED);
+ if (sg_count < 0)
+ return sg_count;
dmaengine_slave_config(chan, &conf);
- desc = dmaengine_prep_slave_sg(chan,
- data->sg,
- host->sg_len,
- conf.direction,
- DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ desc = dmaengine_prep_slave_sg(chan, data->sg, sg_count,
+ conf.direction,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
dev_err(mmc_dev(host->mmc),
"Failed to allocate DMA %s descriptor",
@@ -342,7 +332,8 @@ static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
return 0;
dma_unmap:
- jz4740_mmc_dma_unmap(host, data);
+ if (data->host_cookie == COOKIE_MAPPED)
+ jz4740_mmc_dma_unmap(host, data);
return -ENOMEM;
}
@@ -351,16 +342,13 @@ static void jz4740_mmc_pre_request(struct mmc_host *mmc,
{
struct jz4740_mmc_host *host = mmc_priv(mmc);
struct mmc_data *data = mrq->data;
- struct jz4740_mmc_host_next *next_data = &host->next_data;
- BUG_ON(data->host_cookie);
-
- if (host->use_dma) {
- struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
+ if (!host->use_dma)
+ return;
- if (jz4740_mmc_prepare_dma_data(host, data, next_data, chan))
- data->host_cookie = 0;
- }
+ data->host_cookie = COOKIE_UNMAPPED;
+ if (jz4740_mmc_prepare_dma_data(host, data, COOKIE_PREMAPPED) < 0)
+ data->host_cookie = COOKIE_UNMAPPED;
}
static void jz4740_mmc_post_request(struct mmc_host *mmc,
@@ -370,10 +358,8 @@ static void jz4740_mmc_post_request(struct mmc_host *mmc,
struct jz4740_mmc_host *host = mmc_priv(mmc);
struct mmc_data *data = mrq->data;
- if (host->use_dma && data->host_cookie) {
+ if (data && data->host_cookie != COOKIE_UNMAPPED)
jz4740_mmc_dma_unmap(host, data);
- data->host_cookie = 0;
- }
if (err) {
struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
@@ -436,10 +422,14 @@ static void jz4740_mmc_reset(struct jz4740_mmc_host *host)
static void jz4740_mmc_request_done(struct jz4740_mmc_host *host)
{
struct mmc_request *req;
+ struct mmc_data *data;
req = host->req;
+ data = req->data;
host->req = NULL;
+ if (data && data->host_cookie == COOKIE_MAPPED)
+ jz4740_mmc_dma_unmap(host, data);
mmc_request_done(host->mmc, req);
}
--
2.19.1
