From: Joe Perches <joe@perches.com>
To: "Serge Semin" <Sergey.Semin@baikalelectronics.ru>,
"Jingoo Han" <jingoohan1@gmail.com>,
"Gustavo Pimentel" <gustavo.pimentel@synopsys.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>
Cc: Serge Semin <fancer.lancer@gmail.com>,
Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
Frank Li <Frank.Li@nxp.com>,
Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 03/16] PCI: dwc: Add more verbose link-up message
Date: Mon, 28 Mar 2022 16:31:53 -0700 [thread overview]
Message-ID: <8569d431ce4e1d64ae271f0498c7a0395d2c5c7e.camel@perches.com> (raw)
In-Reply-To: <20220324013734.18234-4-Sergey.Semin@baikalelectronics.ru>
On Thu, 2022-03-24 at 04:37 +0300, Serge Semin wrote:
> Printing just "link up" isn't that much informative especially when it
> comes to working with the PCI Express bus. Even if the link is up, due to
> multiple reasons the bus performance can degrade to slower speeds or to
> narrower width than both Root Port and its partner is capable of. In that
> case it would be handy to know the link specifications as early as
> possible. So let's add a more verbose message to the busy-wait link-state
> method, which will contain the link speed generation and the PCIe bus
> width in case if the link up state is discovered. Otherwise an error will
> be printed to the system log.
>
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> ---
> drivers/pci/controller/dwc/pcie-designware.c | 22 +++++++++++++++-----
> 1 file changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
[]
> @@ -528,14 +528,26 @@ int dw_pcie_wait_for_link(struct dw_pcie *pci)
>
> /* Check if the link is up or not */
> for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) {
> - if (dw_pcie_link_up(pci)) {
> - dev_info(pci->dev, "Link up\n");
> - return 0;
> - }
> + if (dw_pcie_link_up(pci))
> + break;
> +
> usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX);
> }
>
> - dev_info(pci->dev, "Phy link never came up\n");
> + if (retries < LINK_WAIT_MAX_RETRIES) {
> + u32 offset, val;
> +
> + offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> + val = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
> +
> + dev_info(pci->dev, "PCIe Gen.%u x%u link up\n",
> + FIELD_GET(PCI_EXP_LNKSTA_CLS, val),
> + FIELD_GET(PCI_EXP_LNKSTA_NLW, val));
> +
> + return 0;
> + }
> +
> + dev_err(pci->dev, "Phy link never came up\n");
>
> return -ETIMEDOUT;
> }
IMO: it's generally bette to test the error condition and unindent
the typical return.
if (retries >= LINK_WAIT_MAX_RETRIES) {
dev_err(pci->dev, "Phy link never came up\n");
return -ETIMEDOUT;
}
offset = ...
val = ...
dev_info(...)
return 0;
}
next prev parent reply other threads:[~2022-03-28 23:32 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-24 1:37 [PATCH 00/16] PCI: dwc: Add dma-ranges/YAML-schema/Baikal-T1 support Serge Semin
2022-03-24 1:37 ` [PATCH 01/16] dt-bindings: PCI: dwc: Define generic and native DT bindings Serge Semin
2022-03-28 20:46 ` Rob Herring
2022-04-15 16:14 ` Serge Semin
2022-03-24 1:37 ` [PATCH 02/16] dt-bindings: PCI: dwc: Add Baikal-T1 PCIe Root Port bindings Serge Semin
2022-03-28 23:20 ` Rob Herring
2022-04-15 20:22 ` Serge Semin
2022-03-24 1:37 ` [PATCH 03/16] PCI: dwc: Add more verbose link-up message Serge Semin
2022-03-28 23:31 ` Joe Perches [this message]
2022-04-16 8:01 ` Serge Semin
2022-03-29 14:47 ` Rob Herring
2022-04-17 10:10 ` Serge Semin
2022-03-24 1:37 ` [PATCH 04/16] PCI: dwc: Convert to using native IP-core versions representation Serge Semin
2022-03-29 15:00 ` Rob Herring
2022-04-17 14:42 ` Serge Semin
2022-03-24 1:37 ` [PATCH 05/16] PCI: dwc: Add IP-core version detection procedure Serge Semin
2022-03-29 15:08 ` Rob Herring
2022-04-17 15:13 ` Serge Semin
2022-03-24 1:37 ` [PATCH 06/16] PCI: dwc: Introduce Synopsys IP-core versions/types interface Serge Semin
2022-03-24 1:37 ` [PATCH 07/16] PCI: dwc: Add host de-initialization callback Serge Semin
2022-03-24 1:37 ` [PATCH 08/16] PCI: dwc: Drop inbound iATU types enumeration - dw_pcie_as_type Serge Semin
2022-03-29 15:16 ` Rob Herring
2022-03-24 1:37 ` [PATCH 09/16] PCI: dwc: Simplify in/outbound iATU setup methods Serge Semin
2022-03-29 15:28 ` Rob Herring
2022-04-17 20:08 ` Serge Semin
2022-03-24 1:37 ` [PATCH 10/16] PCI: dwc: Drop iATU regions enumeration - dw_pcie_region_type Serge Semin
2022-03-29 15:31 ` Rob Herring
2022-04-17 17:52 ` Serge Semin
2022-03-24 1:37 ` [PATCH 11/16] PCI: dwc: Add iATU regions size detection procedure Serge Semin
2022-03-24 1:37 ` [PATCH 12/16] PCI: dwc: Verify in/out regions against iATU constraints Serge Semin
2022-03-24 1:37 ` [PATCH 13/16] PCI: dwc: Check iATU in/outbound ranges setup methods status Serge Semin
2022-03-24 1:37 ` [PATCH 14/16] PCI: dwc: Introduce dma-ranges property support for RC-host Serge Semin
2022-03-24 1:37 ` [PATCH 15/16] PCI: dwc: Introduce generic platform clocks and resets sets Serge Semin
2022-03-24 1:37 ` [PATCH 16/16] PCI: dwc: Add Baikal-T1 PCIe controller support Serge Semin
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