Re: [PATCH] spi: tegra114: add spi driver

From: Laxman Dewangan
Date: Wed Feb 20 2013 - 08:27:10 EST

On Wednesday 20 February 2013 06:41 PM, Mark Brown wrote:
* PGP Signed by an unknown key

On Wed, Feb 20, 2013 at 05:59:03PM +0530, Laxman Dewangan wrote:
+ tspi->clk = devm_clk_get(&pdev->dev, "spi");
Does this HW block use multiple clocks? If not, I think s/"spi"/NULL/
there, just like the Tegra20 driver.
No, spi controller uses the only one clock. I will change to NULL.
I'm never convinced that NULL is a helpful clock name to pick, it's not
awesome if you ever acquire a second clock.

I had other idea of okeeping clock name here for power optimization.
Spi controller can take the power source ffrom different clock source say clk_m (crystal) and pllp.

I want to set the parent clock dynamically based on required speed so that if the desire speed can be meet from clk_m, no need to increase pll count and possible we may endup with siwtchng off pllp which can save power.

So for this I may require

spi_clk = devm_clk_get(&pdev->dev, "spi");
spi_clkm = devm_clk_get(&pdev->dev, "clmkm");
spi_pllp = devm_clk_get(&pdev->dev, "pllp");

and call clk_set_parent(spi_clk, spi_clkm) or clk_set_parent(spi_clk, spi_pllp).

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