mmc_calc_max_discard compute a worst case : max(erase, trim).
Without this commit, if the erase time is big (2400ms for example) and
max_busy_timeout is 1300ms (sdhci running with a clock at 100Mhz and
SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK), discard support will be disabled.
But trim could be used without exceding max_busy_timeout
Also when using secure trim or erase, the max timeout is much bigger, and it is not checked in mmc_calc_max_discard. So we need to check max_busy_timeout in mmc_do_erase to support all case.
Note I wonder why we don't check status in spi case. Also why can't we use mmc_send_status ?
It that because of the retry ?
But what's weird is that in other case of status poll retry is done (for example card_busy_detect in drivers/mmc/card/block.c)
---
drivers/mmc/core/core.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 7dc0c85..12e69e2 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1952,6 +1952,16 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
cmd.arg = arg;
cmd.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
cmd.busy_timeout = mmc_erase_timeout(card, arg, qty);
+ /*
+ * Normally we use R1B responses, but in cases where the host
+ * has specified a max_busy_timeout we need to validate it. A failure
+ * means we need to prevent the host from doing hw busy detection, which
+ * is done by converting to a R1 response instead.
+ */
+ if (cmd.busy_timeout > host->max_busy_timeout) {
+ cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
+ cmd.busy_timeout = 0;
+ }
err = mmc_wait_for_cmd(card->host, &cmd, 0);
if (err) {
pr_err("mmc_erase: erase error %d, status %#x\n",
@@ -2189,6 +2199,9 @@ unsigned int mmc_calc_max_discard(struct mmc_card *card)
} else if (max_discard < card->erase_size) {
max_discard = 0;
}
+ /* if max_busy_timeout is too small, we can poll */
+ if (!max_discard)
+ max_discard = card->pref_erase;
pr_debug("%s: calculated max. discard sectors %u for timeout %u ms\n",
mmc_hostname(host), max_discard, host->max_busy_timeout);
return max_discard;
--
2.0.1
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