[U-Boot] [PATCH v2 3/3] apalis_t30: fix optional pcie port reset for reliable pcie operation

[Marcel Ziswiler]

On Wed, 2017-08-09 at 12:51 -0600, Stephen Warren wrote:
> On 08/09/2017 09:44 AM, Marcel Ziswiler wrote:
> > From: Marcel Ziswiler <marcel.ziswiler at toradex.com>
> > 
> > Allow optionally bringing up the Apalis type specific 4 lane PCIe
> > port
> > as well as the PCIe switch as found on the Apalis Evaluation board.
> > In
> > order to avoid violating the PCIe reset timing do this by
> > overriding the
> > tegra_pcie_board_port_reset() function. Note however that both the
> > Apalis type specific 4 lane PCIe port as well as the regular Apalis
> > PCIe
> > port are also left disabled in the device tree by default.
> > diff --git a/board/toradex/apalis_t30/apalis_t30.c
> > b/board/toradex/apalis_t30/apalis_t30.c
> > +void tegra_pcie_board_port_reset(struct tegra_pcie_port *port)
> > +			/*
> > +			 * Reset PLX PEX 8605 PCIe Switch plus
> > PCIe devices on
> > +			 * Apalis Evaluation Board
> > +			 */
> > +			gpio_direction_output(PEX_PERST_N, 0);
> > +			gpio_direction_output(RESET_MOCI_CTRL, 0);
> > +
> > +			/*
> > +			 * Must be asserted for 100 ms after power
> > and clocks
> > +			 * are stable
> > +			 */
> > +			mdelay(100);
> > +
> > +			gpio_set_value(PEX_PERST_N, 1);
> > +			/*
> > +			 * Err_5: PEX_REFCLK_OUTpx/nx Clock
> > Outputs is not
> > +			 * Guaranteed Until 900 us After
> > PEX_PERST# De-assertion
> > +			 */
> > +			mdelay(1);
> > +			gpio_set_value(RESET_MOCI_CTRL, 1);
> 
> Don't we need to also call the core tegra_pcie_port_reset() function 
> here, so that the driver gets to do any reset of the PCIe controller
> HW 
> that's required? I think that part should happen irrespective of
> whether 
> CONFIG_APALIS_T30_PCIE_EVALBOARD_INIT is enabled?

I really don't think so. All it really would do is just resetting by the means of the regular PEX_CTL signals which our design is not using like that anyway.