Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1652422

Re: [PATCH 3/4] mmc: sdhci-esdhc-imx: Allow all supported prescaler values

Show all headers | View raw

On Wed, May 3, 2017 at 7:05 AM, Benoît Thébaudeau <benoit@wsystem.com> wrote:
> On i.MX, SYSCTL.SDCLKFS may always be set to 0 in order to make the SD
> clock frequency prescaler divide by 1 in SDR mode, even with the eSDHC.
> The previous minimum prescaler value of 2 in SDR mode with the eSDHC was
> a code remnant from PowerPC, which actually has this limitation on
> earlier revisions.
>
> In DDR mode, the prescaler can divide by up to 512.
>
> The maximum SD clock frequency in High Speed mode is 50 MHz. On i.MX25,
> this change makes it possible to get 48 MHz from the USB PLL
> (240 MHz / 5 / 1) instead of only 40 MHz from the USB PLL
> (240 MHz / 3 / 2) or 33.25 MHz from the AHB clock (133 MHz / 2 / 2).
>
> Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>

Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

Re: [PATCH 3/4] mmc: sdhci-esdhc-imx: Allow all supported prescaler values Fabio Estevam <festevam@gmail.com> - 2017-05-29 13:20 +0200

csiph-web