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idpf: read lower clock bits inside the time sandwich

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PCIe reads need to be done inside the time sandwich because PCIe
writes may get buffered in the PCIe fabric and posted to the device
after the _postts completes. Doing the PCIe read inside the time
sandwich guarantees that the write gets flushed before the _postts
timestamp is taken.

Cc: lrizzo@google.com
Cc: namangulati@google.com
Cc: willemb@google.com
Cc: intel-wired-lan@lists.osuosl.org
Cc: milena.olech@intel.com
Cc: jacob.e.keller@intel.com

Fixes: 5cb8805d23 ("idpf: negotiate PTP capabilities and get PTP clock")
Suggested-by: Shachar Raindel <shacharr@google.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Samuel Salin <Samuel.salin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
This commit is contained in:
Mina Almasry 2025-12-11 10:19:29 +00:00 committed by Tony Nguyen
parent d3f867e7a0
commit bdfc7b55ad
1 changed files with 1 additions and 1 deletions
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2
drivers/net/ethernet/intel/idpf/idpf_ptp.c
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@ -108,11 +108,11 @@ static u64 idpf_ptp_read_src_clk_reg_direct(struct idpf_adapter *adapter,
ptp_read_system_prets(sts);
idpf_ptp_enable_shtime(adapter);
lo = readl(ptp->dev_clk_regs.dev_clk_ns_l);
/* Read the system timestamp post PHC read */
ptp_read_system_postts(sts);
lo = readl(ptp->dev_clk_regs.dev_clk_ns_l);
hi = readl(ptp->dev_clk_regs.dev_clk_ns_h);
spin_unlock(&ptp->read_dev_clk_lock);