[U-Boot] [PATCH v1 1/2] odroid: Update README with USB host information

[Przemyslaw Marczak]

Hello,
On 11/19/2014 05:21 PM, Suriyan Ramasami wrote:
> Add information wrt the USB host side of things for the Odroid-U2/U3 and the
> Odroid-X/X2
>
> Signed-off-by: Suriyan Ramasami <suriyan.r at gmail.com>
> ---
>
> Changes in v1:
> - Add USB host notes for the Odroid
>
>   doc/README.odroid | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 48 insertions(+)
>
> diff --git a/doc/README.odroid b/doc/README.odroid
> index 528bb95..0eaf3ff 100644
> --- a/doc/README.odroid
> +++ b/doc/README.odroid
> @@ -141,3 +141,51 @@ And the boot sequence is:
>   - boot_fit - if "Image.itb" exists
>   - boot_zimg - if "zImage" exists
>   - boot_uimg - if "uImage" exists
> +
> +11. USB host support
> +====================
> +The Odroid-X/X2 have the below schematics wrt USB:
> +
> +Exynos USB_HOST1 -> USB3503 HUB ----> LAN9514 USB HUB -----> LAN9514 Ethernet
> +			|		|
> +			|		+-------Host1---------> USB port
> +			|		|
> +			|		+-------Host2---------> USB port
> +			|		|
> +			|		+-------Host3---------> USB port
> +			|		|
> +			|		+-------Host4---------> USB port
> +			|
> +			+-------------------------------------> USB port
> +			|
> +			+-------------------------------------> USB port
> +
> +The Odroid-U2/U3 have the below schematics wrt USB:
> +
> +Exynos HSIC1 -----------------------------------------------> LAN9514 Ethernet
> +
> +Exynos HSIC2 -----> USB3503A HUB ---------------Host1---------> USB port
> +			|
> +			+-----------------------Host2---------> USB port
> +			|
> +			+-----------------------HOst3---------> USB port (U3)
> +
> +The HSICs are used in the case of the Odroid-Us and the USB Host in the SoC
> +is used in the case of the Odroid-Xs.
> +
> +In drivers/usb/host/ehci-exynos.c, function names starting with exysno4412*
> +have been added to initialize the HSICs and the PHYs.
> +
> +In board/samsung/odroid/odroid.c, function board_usb_init() adds code to
> +initialize the USB3503 hub.
> +The initializing of the USB3503 hub is as defined in the USB3503A spec sheet.
> +Please refer to Figure 4.1 in the Datasheet.
> +a) Set the INT_N (X30) low (Odroid-Us) or high (Odroid-Xs). This is so that the
> +correct REFCLK frequency is selected. 24MHz for Odroid Us and 26MHz for Odroid
> +Xs.
> +b) Disconnect the HUB (Set HUB_CONNECT (X34) to 0)
> +c) Reset the HUB (Set RESET_N (X35) to 0 and then to 1)
> +d) HUB waits for REF_CLK (which we have set appropriately)
> +e) Timeout waiting for HUB configuration stage
> +f) Connect the HUB (Set HUB_CONNECT (X34) to 1)
> +g) Power recycle the LAN9730 which is connected to BUCK8 (Odroid Us)
>

Suriyan, you quite misunderstand my intention. You added really useful 
part of code - now user can read/write data to USB mass storage or boot 
over the Ethernet. Probably you are using this feature. And this is a 
usage of the USB for the user.

For the user - it's not important how it works in the hardware - I would 
like to get some simple instructions, e.g. How to boot Odroid over the 
Ethernet, or how to write data to USB stick. I believe that users read 
this documentation when they starting use of Odroid with the mainline 
U-Boot, and a description of another boot option is welcome here.
It should be "How to start with this board", rather than how to develop 
USB hub driver on it.

Best regards,
-- 
Przemyslaw Marczak
Samsung R&D Institute Poland
Samsung Electronics
p.marczak at samsung.com