kernel/drivers/pci/controller/pcie-brcmstb.c, branch linux-6.9.y

PCI: brcmstb: Fix broken brcm_pcie_mdio_write() polling

2024-03-10T17:56:10Z

The MDIO_WT_DONE() macro tests bit 31, which is always 0 (== done) as readw_poll_timeout_atomic() does a 16-bit read. Replace with the readl variant. [kwilczynski: commit log] Fixes: ca5dcc76314d ("PCI: brcmstb: Replace status loops with read_poll_timeout_atomic()") Link: https://lore.kernel.org/linux-pci/20240217133722.14391-1-wahrenst@gmx.net Signed-off-by: Jonathan Bell Signed-off-by: Stefan Wahren Signed-off-by: Krzysztof Wilczyński Acked-by: Florian Fainelli

PCI: brcmstb: Configure HW CLKREQ# mode appropriate for downstream device

2024-01-11T11:53:00Z

The Broadcom STB/CM PCIe HW core, which is also used in RPi SOCs, must be deliberately set by the PCIe RC HW into one of three mutually exclusive modes: "safe" -- No CLKREQ# expected or required, refclk is always provided. This mode should work for all devices but is not be capable of any refclk power savings. "no-l1ss" -- CLKREQ# is expected to be driven by the downstream device for CPM and ASPM L0s and L1. Provides Clock Power Management, L0s, and L1, but cannot provide L1 substate (L1SS) power savings. If the downstream device connected to the RC is L1SS capable AND the OS enables L1SS, all PCIe traffic may abruptly halt, potentially hanging the system. "default" -- Bidirectional CLKREQ# between the RC and downstream device. Provides ASPM L0s, L1, and L1SS, but not compliant to provide Clock Power Management; specifically, may not be able to meet the T_CLRon max timing of 400ns as specified in "Dynamic Clock Control", section 3.2.5.2.2 of the PCIe Express Mini CEM 2.1 specification. This situation is atypical and should happen only with older devices. Previously, this driver always set the mode to "no-l1ss", as almost all STB/CM boards operate in this mode. But now there is interest in activating L1SS power savings from STB/CM customers, which requires "aspm" mode. In addition, a bug was filed for RPi4 CM platform because most devices did not work in "no-l1ss" mode. Note that the mode is specified by the DT property "brcm,clkreq-mode". If this property is omitted, then "default" mode is chosen. Note: Since L1 substates are now possible, a modification was made regarding an internal bus timeout: During long periods of the PCIe RC HW being in an L1SS sleep state, there may be a timeout on an internal bus access, even though there may not be any PCIe access involved. Such a timeout will cause a subsequent CPU abort. Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217276 Link: https://lore.kernel.org/linux-pci/20231113185607.1756-3-james.quinlan@broadcom.com Tested-by: Cyril Brulebois Tested-by: Florian Fainelli Signed-off-by: Jim Quinlan Signed-off-by: Krzysztof Wilczyński

PCI: brcmstb: Remove stale comment

2023-08-24T15:33:59Z

A comment says that Multi-MSI is not supported by the driver. A past commit [1] added this feature, so the comment is incorrect and is removed. [1] commit 198acab1772f22f2 ("PCI: brcmstb: Enable Multi-MSI") Link: https://lore.kernel.org/r/20230623144100.34196-6-james.quinlan@broadcom.com Signed-off-by: Jim Quinlan Signed-off-by: Lorenzo Pieralisi Acked-by: Florian Fainelli

PCI: brcmstb: Assert PERST# on BCM2711

2023-08-24T15:33:58Z

The current PCIe driver assumes PERST# is asserted when probe() is invoked. Some older versions of the 2711/RPi bootloader left PERST# unasserted, as the Raspian OS does assert PERST# on probe(). For this reason, we assert PERST# for BCM2711 SOCs (i.e. RPi). Link: https://lore.kernel.org/r/20230623144100.34196-5-james.quinlan@broadcom.com Signed-off-by: Jim Quinlan Signed-off-by: Lorenzo Pieralisi

PCI: brcmstb: Convert to platform remove callback returning void

2023-06-24T14:11:01Z

The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is (mostly) ignored and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new() which already returns void. Trivially convert this driver from always returning zero in the remove callback to the void returning variant. Link: https://lore.kernel.org/linux-pci/20230321193208.366561-5-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König Signed-off-by: Krzysztof Wilczyński Acked-by: Florian Fainelli

PCI: brcmstb: Set RCB_{MPS,64B}_MODE bits

2022-11-11T10:42:05Z

Set RCB_MPS mode bit so that data for PCIe read requests up to the size of the Maximum Payload Size (MPS) are returned in one completion, and data for PCIe read requests greater than the MPS are split at the specified Read Completion Boundary setting. Set RCB_64B so that the Read Compeletion Boundary is 64B. Link: https://lore.kernel.org/r/20221011184211.18128-6-jim2101024@gmail.com Signed-off-by: Jim Quinlan Signed-off-by: Lorenzo Pieralisi Acked-by: Florian Fainelli

PCI: brcmstb: Drop needless 'inline' annotations

2022-11-11T10:41:18Z

A number of inline functions are called rarely and/or are not time-critical. Take out the "inline" and let the compiler do its work. Link: https://lore.kernel.org/r/20221011184211.18128-5-jim2101024@gmail.com Signed-off-by: Jim Quinlan Signed-off-by: Lorenzo Pieralisi Reviewed-by: Bjorn Helgaas Acked-by: Florian Fainelli

PCI: brcmstb: Replace status loops with read_poll_timeout_atomic()

2022-11-11T10:40:47Z

It would be nice to replace the PCIe link-up loop as well but there are too many uses of this that do not poll (and the read_poll_timeout uses "timeout==0" to loop forever). Link: https://lore.kernel.org/r/20221011184211.18128-4-jim2101024@gmail.com Signed-off-by: Jim Quinlan Signed-off-by: Lorenzo Pieralisi Acked-by: Florian Fainelli

PCI: brcmstb: Wait for 100ms following PERST# deassert

2022-11-11T10:40:47Z

Be prudent and give some time for power and clocks to become stable. As described in the PCIe CEM specification sections 2.2 and 2.2.1; as well as PCIe r5.0, 6.6.1. Link: https://lore.kernel.org/r/20221011184211.18128-3-jim2101024@gmail.com Signed-off-by: Jim Quinlan Signed-off-by: Lorenzo Pieralisi Acked-by: Florian Fainelli

PCI: brcmstb: Enable Multi-MSI

2022-11-11T10:40:47Z

We always wanted to enable Multi-MSI but didn't have a test device until recently. In addition, there are some devices out there that will ask for multiple MSI but refuse to work if they are only granted one. Link: https://lore.kernel.org/r/20221011184211.18128-2-jim2101024@gmail.com Signed-off-by: Jim Quinlan Signed-off-by: Lorenzo Pieralisi Acked-by: Florian Fainelli