mmc: core: Allow dynamical updates of the number of requests for hsq

To allow dynamical updates of the current number of used in-flight
requests, let's move away from using a hard-coded value to a use a
corresponding variable in the struct mmc_host.

This can be valuable when optimizing for certain I/O request sequences, as
shown by subsequent changes.

Signed-off-by: Wenchao Chen <wenchao.chen@unisoc.com>
Link: https://lore.kernel.org/r/20230919074707.25517-2-wenchao.chen@unisoc.com
[Ulf: Re-wrote the commitmsg to clarify the change]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/mmc/host/mmc_hsq.h b/drivers/mmc/host/mmc_hsq.h
index 1808024fc6c5..aa5c4543b55f 100644
--- a/drivers/mmc/host/mmc_hsq.h
+++ b/drivers/mmc/host/mmc_hsq.h
@@ -5,6 +5,12 @@
 #define HSQ_NUM_SLOTS	64
 #define HSQ_INVALID_TAG	HSQ_NUM_SLOTS
 
+/*
+ * For MMC host software queue, we only allow 2 requests in
+ * flight to avoid a long latency.
+ */
+#define HSQ_NORMAL_DEPTH	2
+
 struct hsq_slot {
 	struct mmc_request *mrq;
 };