[PATCH V3 02/10] mmc: sdhci: allow host to specify maximum tuning loops

Sowjanya Komatineni
2019-03-13T21:45:59Z

As per the Host Controller Standard Specification Version 4.20,
limitation of tuning iteration count is removed as PLL locking
time can be longer than UHS-1 tuning due to larger PVT fluctuation
and it will result in increase of tuning iteration to complete the
tuning.

This patch creates sdhci_host member tuning_loop_count to allow
hosts to specify maximum tuning iterations and also updates
execute_tuning to use this specified maximum tuning iteration count.

Default tuning_loop_count is set to same as existing loop count of
MAX_TUNING_LOOP which is 40 iterations.

Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
drivers/mmc/host/sdhci.c | 5 +++--
drivers/mmc/host/sdhci.h | 1 +
2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index a8141ff9be03..bbc0e0bb7128 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2369,9 +2369,9 @@ static int __sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)

/*
* Issue opcode repeatedly till Execute Tuning is set to 0 or the number
- * of loops reaches 40 times.
+ * of loops reaches tuning loop count.
*/
- for (i = 0; i < MAX_TUNING_LOOP; i++) {
+ for (i = 0; i < host->tuning_loop_count; i++) {
u16 ctrl;

sdhci_send_tuning(host, opcode);
@@ -3494,6 +3494,7 @@ struct sdhci_host *sdhci_alloc_host(struct device *dev,
host->cqe_err_ier = SDHCI_CQE_INT_ERR_MASK;

host->tuning_delay = -1;
+ host->tuning_loop_count = MAX_TUNING_LOOP;

host->sdma_boundary = SDHCI_DEFAULT_BOUNDARY_ARG;

diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 01002cba1359..57bb3e3dca89 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -596,6 +596,7 @@ struct sdhci_host {
#define SDHCI_TUNING_MODE_3 2
/* Delay (ms) between tuning commands */
int tuning_delay;
+ int tuning_loop_count;

/* Host SDMA buffer boundary. */
u32 sdma_boundary;
--
2.7.4