Re: [PATCH] mmc: core: remove waiting time when clkgate_delay is set

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On 2/29/2012 11:22 AM, Chanho Park wrote:
Since recent commit("mmc: core: Use delayed work in clock gating
framework":597dd9d79cfbbb1), we always wait "unnecessary" default
clock delay(8 cycles). Actually, we don't need it if clkgate_delay
(unit:ms) is set because we already wait sufficient time to change
the clock due to delayed_workqueue.
This patch removes duplicated waiting time when clkgate_delay is set.

Signed-off-by: Chanho Park<chanho61.park@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park<kyungmin.park@xxxxxxxxxxx>
---
  drivers/mmc/core/host.c |    7 +++++--
  1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index c3704e2..d710ce0 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -109,8 +109,11 @@ static void mmc_host_clk_gate_delayed(struct mmc_host *host)
  	 */
  	if (!host->clk_requests) {
  		spin_unlock_irqrestore(&host->clk_lock, flags);
-		tick_ns = DIV_ROUND_UP(1000000000, freq);
-		ndelay(host->clk_delay * tick_ns);
+		/* wait only when clk_gate_delay is 0*/

Actually, we should check whether the clkgate_delay is giving sufficient clock cycles instead of just >0 value. But since min. f_min in freq. table is 100KHz (8CLK cyles is ~80us) and clkgate_delay can only specified in milliseconds as of now, I think this should be fine.

+		if (!host->clkgate_delay) {
+			tick_ns = DIV_ROUND_UP(1000000000, freq);
+			ndelay(host->clk_delay * tick_ns);
+		}
  	} else {
  		/* New users appeared while waiting for this work */
  		spin_unlock_irqrestore(&host->clk_lock, flags);

Reviewed-by: Sujit Reddy Thumma <sthumma@xxxxxxxxxxxxxx>

Thanks,
Sujit
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