Subject: Re: [net-next PATCH v2] octeontx2-pf: Use PTP HW timestamp counter atomic update feature

From: Jakub Kicinski <[email-masked]>
Date: Wed, 9 Aug 2023 15:50:22 -0700

On Mon, 7 Aug 2023 19:35:35 +0530 Sai Krishna wrote:
> Some of the newer silicon versions in CN10K series supports a feature
> where in the current PTP timestamp in HW can be updated atomically
> without losing any cpu cycles unlike read/modify/write register.
> This patch uses this feature so that PTP accuracy can be improved
> while adjusting the master offset in HW. There is no need for SW
> timecounter when using this feature. So removed references to SW
> timecounter wherever appropriate.

> -#include "ptp.h"
>  #include "mbox.h"
>  #include "rvu.h"
> +#include "ptp.h"

If you reorder the includes - maybe put them in alphabetical order?

>  static bool cn10k_ptp_errata(struct ptp *ptp)
>  {
> -	if (ptp->pdev->subsystem_device == PCI_SUBSYS_DEVID_CN10K_A_PTP ||
> -	    ptp->pdev->subsystem_device == PCI_SUBSYS_DEVID_CNF10K_A_PTP)
> +	if ((is_ptp_dev_cn10ka(ptp) &&
> +	     ((ptp->pdev->revision & 0x0F) == 0x0 || (ptp->pdev->revision & 0x0F) == 0x1)) ||
> +	    (is_ptp_dev_cnf10ka(ptp) &&
> +	     ((ptp->pdev->revision & 0x0F) == 0x0 || (ptp->pdev->revision & 0x0F) == 0x1)))

Please refactor the revision check to avoid these long lines repeating
the same logic

>  		return true;
> +
>  	return false;
>  }
>  
> -static bool is_ptp_tsfmt_sec_nsec(struct ptp *ptp)
> +static bool is_tstmp_atomic_update_supported(struct rvu *rvu)
>  {
> -	if (ptp->pdev->subsystem_device == PCI_SUBSYS_DEVID_CN10K_A_PTP ||
> -	    ptp->pdev->subsystem_device == PCI_SUBSYS_DEVID_CNF10K_A_PTP)
> -		return true;
> -	return false;
> +	struct ptp *ptp = rvu->ptp;
> +	struct pci_dev *pdev;
> +
> +	if (is_rvu_otx2(rvu))
> +		return false;
> +
> +	pdev = ptp->pdev;
> +
> +	/* On older silicon variants of CN10K, atomic update feature
> +	 * is not available.
> +	 */
> +	if ((pdev->subsystem_device == PCI_SUBSYS_DEVID_CN10K_A_PTP &&
> +	     (pdev->revision & 0x0F) == 0x0) ||
> +	     (pdev->subsystem_device == PCI_SUBSYS_DEVID_CN10K_A_PTP &&
> +	     (pdev->revision & 0x0F) == 0x1) ||
> +	     (pdev->subsystem_device == PCI_SUBSYS_DEVID_CNF10K_A_PTP &&
> +	     (pdev->revision & 0x0F) == 0x0) ||
> +	     (pdev->subsystem_device == PCI_SUBSYS_DEVID_CNF10K_A_PTP &&
> +	     (pdev->revision & 0x0F) == 0x1))

why are you not using cn10k_ptp_errata() here?

> +		return false;
> +
> +	return true;
>  }

> -static int otx2_ptp_adjtime(struct ptp_clock_info *ptp_info, s64 delta)
> +static int otx2_ptp_tc_adjtime(struct ptp_clock_info *ptp_info, s64 delta)
>  {
>  	struct otx2_ptp *ptp = container_of(ptp_info, struct otx2_ptp,
>  					    ptp_info);
>  	struct otx2_nic *pfvf = ptp->nic;
>  
> +	if (!ptp->nic)
> +		return -ENODEV;

Is this check related to the rest of the patch?

>  	mutex_lock(&pfvf->mbox.lock);
>  	timecounter_adjtime(&ptp->time_counter, delta);
>  	mutex_unlock(&pfvf->mbox.lock);
-- 
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