[PATCH 6/8] mmc: dw_mmc: Generic MMC tuning with the clock phase framework
From: jh80.chung@samsung.com (Jaehoon Chung)
Date: 2015-09-16 02:30:32
Also in:
linux-clk, linux-mmc, linux-rockchip, lkml
Hi, On 09/16/2015 07:09 AM, Heiko St?bner wrote:
Hi, Am Dienstag, 15. September 2015, 17:25:38 schrieb Jaehoon Chung:quoted
On 09/01/2015 03:24 AM, Heiko Stuebner wrote:quoted
From: Alexandru M Stan <redacted> This algorithm will try 1 degree increments, since there's no way to tell what resolution the underlying phase code uses. As an added bonus, doing many tunings yields better results since some tests are run more than once (ex: if the underlying driver uses 45 degree increments, the tuning code will try the same angle more than once). It will then construct a list of good phase ranges (even ranges that cross 360/0), will pick the biggest range then it will set the sample_clk to the middle of that range. We do not touch ciu_drive (and by extension define default-drive-phase). Drive phase is mostly used to define minimum hold times, while one could write some code to determine what phase meets the minimum hold time (ex 10 degrees) this will not work with the current clock phase framework (which floors angles, so we'll get 0 deg, and there's no way to know what resolution the floors happen at). We assume that the default drive angles set by the hardware are good enough. If a device has device specific code (like exynos) then that will still take precedence, otherwise this new code will execute. If the device wants to tune, but has no sample_clk defined we'll return EIO with an error message.Which point is "_generic_"? I don't find the code that control the register relevant to CLK_DRV/SMPL PHASE. It seems that posted the similar patches at u-boot mailing list..The "generic" part is that it uses the clk phase API for dw_mmc implementations where the clkgen controlling interface is outside the dw_mmc IP itself. So it's open for other implementations as well.
Designware IP also has the CLK phase register(UHS_REG_EXT register)... if this code is related with it, it should be located into dw-mmc.c.
But if you are more comfortable with it, I can also move it into the dw_mmc- rockchip variant for the time being, until another user comes along.
I think more better that this code is located into dw_mmc-rockchip. how about? Best Regards, Jaehoon Chung
Heiko