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Subject[PATCH 4/8] PCI: iproc: Fix PCIe reset logic
Date
The current iProc PCIe reset logic does not always properly reset the
device. For example, in the case when the perst_b signal is already
de-asserted in the bootloader, the current reset logic fails to trigger
a proper asssert -> de-assert reset sequence. This patch fixes the issue
by always triggering the proper reset sequence

This patch also explicitly selects the desired reset source, i.e.,
perst_b and reduces the wait time after the device comes out of reset
from 250 ms to 100 ms, based on recommendation from the ASIC team

Signed-off-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Vladimir Dreizin <vdreizin@broadcom.com>
Reviewed-by: Trac Hoang <trhoang@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Tested-by: Vladimir Dreizin <vdreizin@broadcom.com>
Tested-by: Darren Edamura <dedamura@broadcom.com>
---
drivers/pci/host/pcie-iproc.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c
index 52e7ff2..80e0541 100644
--- a/drivers/pci/host/pcie-iproc.c
+++ b/drivers/pci/host/pcie-iproc.c
@@ -31,6 +31,8 @@
#include "pcie-iproc.h"

#define CLK_CONTROL_OFFSET 0x000
+#define EP_PERST_SOURCE_SELECT_SHIFT 2
+#define EP_PERST_SOURCE_SELECT BIT(EP_PERST_SOURCE_SELECT_SHIFT)
#define EP_MODE_SURVIVE_PERST_SHIFT 1
#define EP_MODE_SURVIVE_PERST BIT(EP_MODE_SURVIVE_PERST_SHIFT)
#define RC_PCIE_RST_OUTPUT_SHIFT 0
@@ -119,15 +121,18 @@ static void iproc_pcie_reset(struct iproc_pcie *pcie)
u32 val;

/*
- * Configure the PCIe controller as root complex and send a downstream
- * reset
+ * Select perst_b signal as reset source. Put the device into reset,
+ * and then bring it out of reset
*/
- val = EP_MODE_SURVIVE_PERST | RC_PCIE_RST_OUTPUT;
+ val = readl(pcie->base + CLK_CONTROL_OFFSET);
+ val &= ~EP_PERST_SOURCE_SELECT & ~EP_MODE_SURVIVE_PERST &
+ ~RC_PCIE_RST_OUTPUT;
writel(val, pcie->base + CLK_CONTROL_OFFSET);
udelay(250);
- val &= ~EP_MODE_SURVIVE_PERST;
+
+ val |= RC_PCIE_RST_OUTPUT;
writel(val, pcie->base + CLK_CONTROL_OFFSET);
- msleep(250);
+ msleep(100);
}

static int iproc_pcie_check_link(struct iproc_pcie *pcie, struct pci_bus *bus)
--
1.9.1


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