[PATCH] arm64: dts: hi6220: improve g-tx-fifo-size setting for usb device

[John Stultz]

On Sun, Aug 6, 2017 at 10:01 PM, Shawn Guo <shawnguo at kernel.org> wrote:
> From: Shawn Guo <shawn.guo at linaro.org>
>
> The current usb device g-tx-fifo-size setting in DT causes two problems
> for kernel driver.
>
> 1. On hi6220, there are 15 tx_fifo dedicated for all EPs except EP0,
>    while DT only provides tx_fifo settings for 6 EPs.  It results in the
>    following annoying complaints from kernel.
>
> [    4.451623] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[7]=0
> [    4.461303] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[8]=0
> [    4.470969] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[9]=0
> [    4.480632] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[10]=0
> [    4.490385] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[11]=0
> [    4.500140] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[12]=0
> [    4.509892] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[13]=0
> [    4.519646] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[14]=0
> [    4.529399] dwc2 f72c0000.usb: dwc2_check_param_tx_fifo_sizes: Invalid parameter g_tx_fifo_size[15]=0
> [    4.539244] dwc2 f72c0000.usb: EPs: 16, dedicated fifos, 1920 entries in SPRAM
>
>    Besides of that, the total 1920 fifo entries isn't fully utilized.
>    Endpoint Info Control block consumes 128 entries, g-rx-fifo-size
>    is 512, and g-np-tx-fifo-size is 128.  So the fifi entries available
>    for tx_fifo is: 1920 - 128 - 512 - 128 = 1152.  Considering that
>    the minimal valid tx_fifo size for each EP is 16, it should be
>    reasonable to allocate 1152 entries as: 128 x 8 + 16 x 7 = 1136 (only
>    16 entries unused).  With this new setting, we can get more EPs to
>    use while removing the above warning messages in the meantime.
>
> 2. Another consequence of above invalid g_tx_fifo_size parameter is that
>    kernel driver will use values read from hardware register as the
>    fall-back.  The value is 2048 for each EP fifo.  That's obviously
>    invalid either, because even fifo entries for one EP exceeds the
>    total entries 1920.  That's why we see the following fat warning from
>    function dwc2_hsotg_init_fifo().  The new g-tx-fifo-size settings
>    help to remove the warning as well.


Nice! This has been bothering me for awhile, and your fix seems to
resolve it well! I can now remove one of the hack patches I've been
carrying.

Tested-by: John Stultz <john.stultz at linaro.org>
(if its useful: Acked-by: John Stultz <john.stultz at linaro.org>)

Wei: Can we be sure to get this queued for 4.14?

thanks
-john