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Date: Fri, 14 Jun 2024 11:26:53 -0400
From: Sean Anderson <sean.anderson@...ux.dev>
To: "Pandey, Radhey Shyam" <radhey.shyam.pandey@....com>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
"linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>
Cc: Vinod Koul <vkoul@...nel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Simek, Michal" <michal.simek@....com>,
Kishon Vijay Abraham I <kishon@...nel.org>
Subject: Re: [PATCH v2 4/4] phy: zynqmp: Add debugfs support
On 6/14/24 01:16, Pandey, Radhey Shyam wrote:
>> -----Original Message-----
>> From: Sean Anderson <sean.anderson@...ux.dev>
>> Sent: Thursday, June 13, 2024 8:32 PM
>> To: Pandey, Radhey Shyam <radhey.shyam.pandey@....com>; Laurent
>> Pinchart <laurent.pinchart@...asonboard.com>; linux-
>> phy@...ts.infradead.org
>> Cc: Vinod Koul <vkoul@...nel.org>; linux-arm-kernel@...ts.infradead.org;
>> linux-kernel@...r.kernel.org; Simek, Michal <michal.simek@....com>;
>> Kishon Vijay Abraham I <kishon@...nel.org>
>> Subject: Re: [PATCH v2 4/4] phy: zynqmp: Add debugfs support
>>
>> On 6/13/24 05:20, Pandey, Radhey Shyam wrote:
>> >> -----Original Message-----
>> >> From: Sean Anderson <sean.anderson@...ux.dev>
>> >> Sent: Monday, May 6, 2024 10:31 PM
>> >> To: Laurent Pinchart <laurent.pinchart@...asonboard.com>; linux-
>> >> phy@...ts.infradead.org
>> >> Cc: Vinod Koul <vkoul@...nel.org>; linux-arm-kernel@...ts.infradead.org;
>> >> linux-kernel@...r.kernel.org; Michal Simek <michal.simek@....com>;
>> >> Kishon Vijay Abraham I <kishon@...nel.org>; Sean Anderson
>> >> <sean.anderson@...ux.dev>
>> >> Subject: [PATCH v2 4/4] phy: zynqmp: Add debugfs support
>> >>
>> >> Add support for printing some basic status information to debugfs. This
>> >> is helpful when debugging phy consumers to make sure they are
>> configuring
>> >> the phy appropriately.
>> >>
>> >> Signed-off-by: Sean Anderson <sean.anderson@...ux.dev>
>> >> ---
>> >>
>> >> Changes in v2:
>> >> - Use debugfs_create_devm_seqfile
>> >>
>> >> drivers/phy/xilinx/phy-zynqmp.c | 40
>> >> +++++++++++++++++++++++++++++++++
>> >> 1 file changed, 40 insertions(+)
>> >>
>> >> diff --git a/drivers/phy/xilinx/phy-zynqmp.c b/drivers/phy/xilinx/phy-
>> >> zynqmp.c
>> >> index b86fe2a249a8..2520c75a4a77 100644
>> >> --- a/drivers/phy/xilinx/phy-zynqmp.c
>> >> +++ b/drivers/phy/xilinx/phy-zynqmp.c
>> >> @@ -13,6 +13,7 @@
>> >> */
>> >>
>> >> #include <linux/clk.h>
>> >> +#include <linux/debugfs.h>
>> >> #include <linux/delay.h>
>> >> #include <linux/io.h>
>> >> #include <linux/kernel.h>
>> >> @@ -123,6 +124,15 @@
>> >> #define ICM_PROTOCOL_DP 0x4
>> >> #define ICM_PROTOCOL_SGMII 0x5
>> >>
>> >> +static const char *const xpsgtr_icm_str[] = {
>> >> + [ICM_PROTOCOL_PD] = "powered down",
>> >
>> > Protocol saying powered down seems confusing.
>> > Should we say None or None(power down)?
>>
>> Either works I guess. I'm just matching the define.
>
> None seems fine - we can respin if there are no objections.
>>
>> >> + [ICM_PROTOCOL_PCIE] = "PCIe",
>> >> + [ICM_PROTOCOL_SATA] = "SATA",
>> >> + [ICM_PROTOCOL_USB] = "USB",
>> >> + [ICM_PROTOCOL_DP] = "DisplayPort",
>> >> + [ICM_PROTOCOL_SGMII] = "SGMII",
>> >> +};
>> >> +
>> >> /* Test Mode common reset control parameters */
>> >> #define TM_CMN_RST 0x10018
>> >> #define TM_CMN_RST_EN 0x1
>> >> @@ -788,6 +798,34 @@ static struct phy *xpsgtr_xlate(struct device *dev,
>> >> return ERR_PTR(-EINVAL);
>> >> }
>> >>
>> >> +/*
>> >> + * DebugFS
>> >> + */
>> >> +
>> >> +static int xpsgtr_status_read(struct seq_file *seq, void *data)
>> >> +{
>> >> + struct device *dev = seq->private;
>> >> + struct xpsgtr_phy *gtr_phy = dev_get_drvdata(dev);
>> >> + struct clk *clk;
>> >> + u32 pll_status;
>> >> +
>> >> + mutex_lock(>r_phy->phy->mutex);
>> >
>> > Do we see any need for this lock? This function simply read hw register
>> > /phy members and decodes it.
>>
>> It's to protect against modifications to gtr_phy->refclk and ->instance.
>
> Refclock and instance is assigned in xlate which is not protected by any
> Lock. Also xpsgtr_phy_init () uses a different gtr_mutex. So want
> to understand this phy->mutex need.
Ah, well then we should take this lock in xlate.
--Sean
>>
>> These are accessed under lock elsewhere; this is not a fast path and I don't
>> want to have to reason about the semantics when using a mutex is definitely
>> correct.
>>
>> --Sean
>>
>> >> + pll_status = xpsgtr_read_phy(gtr_phy, L0_PLL_STATUS_READ_1);
>> >> + clk = gtr_phy->dev->clk[gtr_phy->refclk];
>> >> +
>> >> + seq_printf(seq, "Lane: %u\n", gtr_phy->lane);
>> >> + seq_printf(seq, "Protocol: %s\n",
>> >> + xpsgtr_icm_str[gtr_phy->protocol]);
>> >> + seq_printf(seq, "Instance: %u\n", gtr_phy->instance);
>> >> + seq_printf(seq, "Reference clock: %u (%pC)\n", gtr_phy->refclk, clk);
>> >> + seq_printf(seq, "Reference rate: %lu\n", clk_get_rate(clk));
>> >> + seq_printf(seq, "PLL locked: %s\n",
>> >> + pll_status & PLL_STATUS_LOCKED ? "yes" : "no");
>> >> +
>> >> + mutex_unlock(>r_phy->phy->mutex);
>> >> + return 0;
>> >> +}
>> >> +
>> >> /*
>> >> * Power Management
>> >> */
>> >> @@ -937,6 +975,8 @@ static int xpsgtr_probe(struct platform_device
>> *pdev)
>> >>
>> >> gtr_phy->phy = phy;
>> >> phy_set_drvdata(phy, gtr_phy);
>> >> + debugfs_create_devm_seqfile(&phy->dev, "status", phy-
>> >> >debugfs,
>> >> + xpsgtr_status_read);
>> >> }
>> >>
>> >> /* Register the PHY provider. */
>> >> --
>> >> 2.35.1.1320.gc452695387.dirty
>> >
>
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