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mmc: sdricoh_cs: Throttle polling rate for commands

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Rather than to poll in a busy-loop, let's convert into using
read_poll_timeout() and insert a small delay between each polling attempts.
In particular, this avoids hogging the CPU.

Additionally, to convert to read_poll_timeout() we also need to switch from
using a specific number of polling attempts, into a specific timeout in us
instead. The previous 100000 attempts, is translated into a total timeout
of total 1s, as that seemed like reasonable value to pick.

Cc: Sascha Sommer <saschasommer@freenet.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20200508095218.14177-1-ulf.hansson@linaro.org
This commit is contained in:
Ulf Hansson 2020-05-08 11:52:18 +02:00
parent eadb789765
commit 3eea697c1d
1 changed files with 16 additions and 17 deletions
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35
drivers/mmc/host/sdricoh_cs.c
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@ -59,7 +59,7 @@ static unsigned int switchlocked;
#define STATUS_BUSY 0x40000000
/* timeouts */
#define CMD_TIMEOUT 100000
#define SDRICOH_CMD_TIMEOUT_US 1000000
#define SDRICOH_DATA_TIMEOUT_US 1000000
/* list of supported pcmcia devices */
@ -158,8 +158,7 @@ static int sdricoh_query_status(struct sdricoh_host *host, unsigned int wanted)
static int sdricoh_mmc_cmd(struct sdricoh_host *host, struct mmc_command *cmd)
{
unsigned int status;
int result = 0;
unsigned int loop = 0;
int ret;
unsigned char opcode = cmd->opcode;
/* reset status reg? */
@ -175,24 +174,24 @@ static int sdricoh_mmc_cmd(struct sdricoh_host *host, struct mmc_command *cmd)
/* fill parameters */
sdricoh_writel(host, R204_CMD_ARG, cmd->arg);
sdricoh_writel(host, R200_CMD, (0x10000 << 8) | opcode);
/* wait for command completion */
if (opcode) {
for (loop = 0; loop < CMD_TIMEOUT; loop++) {
status = sdricoh_readl(host, R21C_STATUS);
sdricoh_writel(host, R2E4_STATUS_RESP, status);
if (status & STATUS_CMD_FINISHED)
break;
}
/* don't check for timeout in the loop it is not always
reset correctly
if (!opcode)
return 0;
ret = read_poll_timeout(sdricoh_readl, status,
sdricoh_status_ok(host, status, STATUS_CMD_FINISHED),
32, SDRICOH_CMD_TIMEOUT_US, false,
host, R21C_STATUS);
/*
* Don't check for timeout status in the loop, as it's not always reset
* correctly.
*/
if (loop == CMD_TIMEOUT || status & STATUS_CMD_TIMEOUT)
result = -ETIMEDOUT;
}
return result;
if (ret || status & STATUS_CMD_TIMEOUT)
return -ETIMEDOUT;
return 0;
}
static int sdricoh_reset(struct sdricoh_host *host)