From mboxrd@z Thu Jan 1 00:00:00 1970 From: stanimir.varbanov@linaro.org (Stanimir Varbanov) Date: Thu, 3 Dec 2015 15:35:20 +0200 Subject: [PATCH v4 1/5] PCI: designware: add memory barrier after enabling region In-Reply-To: <1449149725-27607-1-git-send-email-stanimir.varbanov@linaro.org> References: <1449149725-27607-1-git-send-email-stanimir.varbanov@linaro.org> Message-ID: <1449149725-27607-2-git-send-email-stanimir.varbanov@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Add 'write memory' barrier after enable region in PCIE_ATU_CR2 register. The barrier is needed to ensure that the region enable request has been reached it's destination at time when we read/write to PCI configuration space. Without this barrier PCI device enumeration during kernel boot is not reliable, and reading configuration space for particular PCI device on the bus returns zero aka no device. Signed-off-by: Stanimir Varbanov --- drivers/pci/host/pcie-designware.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c index 02a7452bdf23..ed4dc2e2553b 100644 --- a/drivers/pci/host/pcie-designware.c +++ b/drivers/pci/host/pcie-designware.c @@ -164,6 +164,11 @@ static void dw_pcie_prog_outbound_atu(struct pcie_port *pp, int index, dw_pcie_writel_rc(pp, upper_32_bits(pci_addr), PCIE_ATU_UPPER_TARGET); dw_pcie_writel_rc(pp, type, PCIE_ATU_CR1); dw_pcie_writel_rc(pp, PCIE_ATU_ENABLE, PCIE_ATU_CR2); + /* + * ensure that the ATU enable has been happaned before accessing + * pci configuration/io spaces through dw_pcie_cfg_[read|write]. + */ + wmb(); } static struct irq_chip dw_msi_irq_chip = { -- 1.7.9.5