From: Siddharth Vadapalli <s-vadapalli@ti.com>
Date: Sun, 12 Apr 2026 06:46:17 +0000 (+0530)
Subject: doc: board: ti: j784s4_evm: Automate BAR address lookup for PCIe Boot
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=98d1d3227e8d9513a2705e9fa4c8aa9d20d8eeac;p=thirdparty%2Fu-boot.git

doc: board: ti: j784s4_evm: Automate BAR address lookup for PCIe Boot

When the J784S4-EVM is configured for PCIe Boot, the Bootloaders are to
be written to the address specified by particular BARs. The existing
documentation hard-codes the address corresponding to the BAR under the
assumption that the Root-Complex transferring the Bootloaders is also
a J784S4-EVM. The Root-Complex assigns addresses to the BARs depending
on the currently available set of free system addresses. Since the free
system addresses vary with the Root-Complex being used, instead of
hard-coding the BARs, automate the process of identifying the appropriate
BAR in the form of a command to be run by the user on the Root-Complex.

Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
---

diff --git a/doc/board/ti/j784s4_evm.rst b/doc/board/ti/j784s4_evm.rst
index fb767bedbf6..ec82228ab90 100644
--- a/doc/board/ti/j784s4_evm.rst
+++ b/doc/board/ti/j784s4_evm.rst
@@ -456,12 +456,12 @@ The following steps describe the process of booting J784S4-EVM over PCIe:
       0000:01:00.1 Non-VGA unclassified device: Texas Instruments Device 0100
       0000:01:00.2 Non-VGA unclassified device: Texas Instruments Device 0100
 
-4. Copy ``tiboot3.bin`` to the endpoint. Use ``lspci -vv`` to identify the BAR
-   address:
+4. Copy ``tiboot3.bin`` to BAR1 of Physical Function Zero of the endpoint:
 
    .. prompt:: bash
 
-      sudo ./pcie_boot_util 0x4007100000 tiboot3.bin
+      tiboot3_bar_address="0x$(lspci -D -nnvv | awk '/^[0-9a-fA-F]{4}:/ {bdf=$1; ram=($0 ~ /RAM memory/ || $0 ~ /Memory controller/)} ram && /Region [1]+:/ {print bdf, $0}' | cut -d ' ' -f 6)"
+      sudo ./pcie_boot_util ${tiboot3_bar_address} tiboot3.bin
 
    The sample program automatically writes the image start address to
    ``0x41CF3FE0`` and the magic word ``0xB17CEAD9`` to ``0x41CF3FE4``.
@@ -491,11 +491,12 @@ The following steps describe the process of booting J784S4-EVM over PCIe:
       (with appropriate DOMAIN:BUS:DEVICE.FUNCTION corresponding to the Endpoint) to enable
       the BAR.
 
-6. Copy ``tispl.bin`` to the new BAR address (use ``lspci -vv`` to find):
+6. Copy ``tispl.bin`` to BAR0 of Physical Function Zero of the endpoint:
 
    .. prompt:: bash
 
-      sudo ./pcie_boot_util 0x4000400000 tispl.bin
+      tispl_bar_address="0x$(lspci -D -nnvv | awk '/^[0-9a-fA-F]{4}:/ {bdf=$1; ram=($0 ~ /RAM memory/ || $0 ~ /Memory controller/)} ram && /Region [0]+:/ {print bdf, $0}' | head -n1 | cut -d ' ' -f 6)"
+      sudo ./pcie_boot_util ${tispl_bar_address} tispl.bin
 
 7. After ``tispl.bin`` is processed, the PCIe link will go down again. Remove
    and rescan the PCIe device:
@@ -505,11 +506,12 @@ The following steps describe the process of booting J784S4-EVM over PCIe:
       echo 1 > /sys/bus/pci/devices/0000\:01\:00.0/remove
       echo 1 > /sys/bus/pci/devices/0000\:00\:00.0/rescan
 
-8. Copy ``u-boot.img``:
+8. Copy ``u-boot.img`` to BAR0 of Physical Function Zero of the endpoint:
 
    .. prompt:: bash
 
-      sudo ./pcie_boot_util 0x4000400000 u-boot.img
+      uboot_bar_address="0x$(lspci -D -nnvv | awk '/^[0-9a-fA-F]{4}:/ {bdf=$1; ram=($0 ~ /RAM memory/ || $0 ~ /Memory controller/)} ram && /Region [0]+:/ {print bdf, $0}' | head -n1 | cut -d ' ' -f 6)"
+      sudo ./pcie_boot_util ${uboot_bar_address} u-boot.img
 
 9. After ``u-boot.img`` is successfully loaded, the boot process is complete
    and endpoint should boot till U-Boot prompt.