[PATCH V1 02/11] mmc: sdhci: allow host to specify maximum tuning loops

Sowjanya Komatineni
2019-03-02T05:20:46Z

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 a hook get_max_tuning_loop_count to allow hosts
to specify maximum tuning iterations and updates execute_tuning
to use the specified maximum tuning iteration count.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
drivers/mmc/host/sdhci.c | 7 +++++--
drivers/mmc/host/sdhci.h | 1 +
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index a8141ff9be03..e9e919218006 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2366,12 +2366,15 @@ EXPORT_SYMBOL_GPL(sdhci_send_tuning);
static int __sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
{
int i;
+ int tuning_loop_count = MAX_TUNING_LOOP;

+ if (host->ops->get_max_tuning_loop_count)
+ tuning_loop_count = host->ops->get_max_tuning_loop_count(host);
/*
* 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 < tuning_loop_count; i++) {
u16 ctrl;

sdhci_send_tuning(host, opcode);
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 01002cba1359..c80e0d6f9b10 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -638,6 +638,7 @@ struct sdhci_ops {
unsigned int (*get_ro)(struct sdhci_host *host);
void (*reset)(struct sdhci_host *host, u8 mask);
int (*platform_execute_tuning)(struct sdhci_host *host, u32 opcode);
+ int (*get_max_tuning_loop_count)(struct sdhci_host *host);
void (*set_uhs_signaling)(struct sdhci_host *host, unsigned int uhs);
void (*hw_reset)(struct sdhci_host *host);
void (*adma_workaround)(struct sdhci_host *host, u32 intmask);
--
2.7.4