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drivers: mmc: preallocate a block for SD extension register accesses

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The Performance Extension register is regularly accessed in a hot path
to do write cache flushes. Don't invoke kmalloc/kfree for every access,
preallocate a 512B buffer for this purpose.

Also remove an unused alloc in sd_enable_cache().

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
This commit is contained in:
Jonathan Bell
2024-03-20 13:00:30 +00:00
committed by Dom Cobley
parent ab227dde54
commit 15d7e6c313
3 changed files with 14 additions and 23 deletions
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2
drivers/mmc/core/bus.c
View File

@@ -266,6 +266,8 @@ static void mmc_release_card(struct device *dev)
sdio_free_common_cis(card);
kfree(card->ext_reg_buf);
kfree(card->info);
kfree(card);

34
drivers/mmc/core/sd.c
View File

@@ -1044,9 +1044,8 @@ int sd_write_ext_reg(struct mmc_card *card, u8 fno, u8 page, u16 offset,
struct scatterlist sg;
u8 *reg_buf;
reg_buf = kzalloc(512, GFP_KERNEL);
if (!reg_buf)
return -ENOMEM;
reg_buf = card->ext_reg_buf;
memset(reg_buf, 0, 512);
mrq.cmd = &cmd;
mrq.data = &data;
@@ -1078,8 +1077,6 @@ int sd_write_ext_reg(struct mmc_card *card, u8 fno, u8 page, u16 offset,
mmc_set_data_timeout(&data, card);
mmc_wait_for_req(host, &mrq);
kfree(reg_buf);
/*
* Note that, the SD card is allowed to signal busy on DAT0 up to 1s
* after the CMD49. Although, let's leave this to be managed by the
@@ -1120,9 +1117,7 @@ static int sd_parse_ext_reg_power(struct mmc_card *card, u8 fno, u8 page,
int err;
u8 *reg_buf;
reg_buf = kzalloc(512, GFP_KERNEL);
if (!reg_buf)
return -ENOMEM;
reg_buf = card->ext_reg_buf;
/* Read the extension register for power management function. */
err = sd_read_ext_reg(card, fno, page, offset, 512, reg_buf);
@@ -1152,7 +1147,6 @@ static int sd_parse_ext_reg_power(struct mmc_card *card, u8 fno, u8 page,
card->ext_power.offset = offset;
out:
kfree(reg_buf);
return err;
}
@@ -1162,9 +1156,7 @@ static int sd_parse_ext_reg_perf(struct mmc_card *card, u8 fno, u8 page,
int err;
u8 *reg_buf;
reg_buf = kzalloc(512, GFP_KERNEL);
if (!reg_buf)
return -ENOMEM;
reg_buf = card->ext_reg_buf;
err = sd_read_ext_reg(card, fno, page, offset, 512, reg_buf);
if (err) {
@@ -1207,7 +1199,6 @@ static int sd_parse_ext_reg_perf(struct mmc_card *card, u8 fno, u8 page,
card->ext_perf.offset = offset;
out:
kfree(reg_buf);
return err;
}
@@ -1278,6 +1269,12 @@ static int sd_read_ext_regs(struct mmc_card *card)
if (!gen_info_buf)
return -ENOMEM;
card->ext_reg_buf = kzalloc(512, GFP_KERNEL);
if (!card->ext_reg_buf) {
err = -ENOMEM;
goto out;
}
/*
* Read 512 bytes of general info, which is found at function number 0,
* at page 0 and with no offset.
@@ -1344,9 +1341,7 @@ static int sd_flush_cache(struct mmc_host *host)
if (!sd_cache_enabled(host))
return 0;
reg_buf = kzalloc(512, GFP_KERNEL);
if (!reg_buf)
return -ENOMEM;
reg_buf = card->ext_reg_buf;
/*
* Set Flush Cache at bit 0 in the performance enhancement register at
@@ -1382,21 +1377,15 @@ static int sd_flush_cache(struct mmc_host *host)
if (reg_buf[0] & BIT(0))
err = -ETIMEDOUT;
out:
kfree(reg_buf);
return err;
}
static int sd_enable_cache(struct mmc_card *card)
{
u8 *reg_buf;
int err;
card->ext_perf.feature_enabled &= ~SD_EXT_PERF_CACHE;
reg_buf = kzalloc(512, GFP_KERNEL);
if (!reg_buf)
return -ENOMEM;
/*
* Set Cache Enable at bit 0 in the performance enhancement register at
* 260 bytes offset.
@@ -1415,7 +1404,6 @@ static int sd_enable_cache(struct mmc_card *card)
card->ext_perf.feature_enabled |= SD_EXT_PERF_CACHE;
out:
kfree(reg_buf);
return err;
}

1
include/linux/mmc/card.h
View File

@@ -355,6 +355,7 @@ struct mmc_card {
struct sd_switch_caps sw_caps; /* switch (CMD6) caps */
struct sd_ext_reg ext_power; /* SD extension reg for PM */
struct sd_ext_reg ext_perf; /* SD extension reg for PERF */
u8 *ext_reg_buf; /* 512 byte block for extension register R/W */
struct sd_uhs2_config uhs2_config; /* SD UHS-II config */