From: Manivannan Sadhasivam <mani@kernel.org>
To: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: linux-phy@lists.infradead.org, Vinod Koul <vkoul@kernel.org>,
Neil Armstrong <neil.armstrong@linaro.org>,
dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org,
linux-arm-kernel@lists.infradead.org,
linux-arm-msm@vger.kernel.org, linux-can@vger.kernel.org,
linux-gpio@vger.kernel.org, linux-ide@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
linux-pci@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-riscv@lists.infradead.org,
linux-rockchip@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-sunxi@lists.linux.dev, linux-tegra@vger.kernel.org,
linux-usb@vger.kernel.org, netdev@vger.kernel.org,
spacemit@lists.linux.dev, UNGLinuxDriver@microchip.com,
"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Nitin Rawat <quic_nitirawa@quicinc.com>
Subject: Re: [PATCH v5 phy-next 10/27] scsi: ufs: qcom: keep parallel track of PHY power state
Date: Wed, 25 Mar 2026 17:21:14 +0530 [thread overview]
Message-ID: <vu3cxpynr5mu2fzkrtmjcwijc5jz323wlnbc3r7lp2wxqmhydx@z5xhgf4myw2d> (raw)
In-Reply-To: <20260325114309.3k7xkfrffpxp5xq4@skbuf>
On Wed, Mar 25, 2026 at 01:43:09PM +0200, Vladimir Oltean wrote:
> On Tue, Mar 24, 2026 at 11:00:10AM +0530, Manivannan Sadhasivam wrote:
> > On Fri, Mar 20, 2026 at 12:32:24AM +0200, Vladimir Oltean wrote:
> > > As explained in the similar ufs-exynos.c change, PHY consumer drivers
> > > should not look at the phy->power_count, because in the general case
> > > there might also be other consumers who have called phy_power_on() too,
> > > so the fact that the power_count is non-zero does not mean that we did.
> > >
> > > Moreover, struct phy will become opaque soon, so the qcom UFS driver
> > > will not be able to apply this pattern. Keep parallel track of the PHY
> > > power state, instead of looking at a field which will become unavailable
> > > (phy->power_count).
> > >
> > > About treating the phy_power_off() return code: from an API perspective,
> > > this should have probably returned void, otherwise consumers would be
> > > stuck in a state they can't escape. The provider, phy-qcom-qmp-ufs.c,
> > > does return 0 in its power_off() implementation. I consider it safe to
> > > discard potential errors from phy_power_off() instead of complicating
> > > the phy_powered_on logic.
> > >
> >
> > You could even simplify the code by getting rid of the 'phy_powered_on' check
> > altogether. There is no real need to track the PHY power state in this driver.
> > It is safe to call phy_power_off() without any checks.
> >
> > - Mani
>
> Ok.. as the author of commit 7bac65687510 ("scsi: ufs: qcom: Power off
> the PHY if it was already powered on in ufs_qcom_power_up_sequence()"),
> I assume you have hardware to test. Would you mind writing a patch that
> I could pick up to replace this one with?
>
Sure, will do.
> I suppose that the power_count test is somehow no longer necessary after
> commit 77d2fa54a945 ("scsi: ufs: qcom : Refactor phy_power_on/off
> calls"), but frankly I don't see it - the ufshcd state machine is a bit
> too complicated for me to just statically analyze.
I believe I added the power_count check for phy_exit(). But since that got
moved, the check becomes no longer necessary.
- Mani
--
மணிவண்ணன் சதாசிவம்
next prev parent reply other threads:[~2026-03-25 11:51 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-19 22:32 [PATCH v5 phy-next 00/27] Split Generic PHY consumer and provider API Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 01/27] ata: add <linux/pm_runtime.h> where missing Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 02/27] PCI: Add missing headers transitively included by <linux/phy/phy.h> Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 03/27] usb: add " Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 04/27] drm: add <linux/pm_runtime.h> where missing Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 05/27] phy: " Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 06/27] phy: spacemit: include missing <linux/phy/phy.h> Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 07/27] net: lan969x: include missing <linux/of.h> Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 08/27] PCI: Remove device links to PHY Vladimir Oltean
2026-03-24 5:35 ` Manivannan Sadhasivam
2026-03-19 22:32 ` [PATCH v5 phy-next 09/27] scsi: ufs: exynos: stop poking into struct phy guts Vladimir Oltean
2026-03-20 2:15 ` Martin K. Petersen
2026-03-20 8:22 ` Vladimir Oltean
2026-03-23 11:58 ` Vladimir Oltean
2026-03-23 12:35 ` Alim Akhtar
2026-03-23 22:41 ` Vladimir Oltean
2026-03-23 17:26 ` Alim Akhtar
2026-03-19 22:32 ` [PATCH v5 phy-next 10/27] scsi: ufs: qcom: keep parallel track of PHY power state Vladimir Oltean
2026-03-24 5:30 ` Manivannan Sadhasivam
2026-03-25 11:43 ` Vladimir Oltean
2026-03-25 11:51 ` Manivannan Sadhasivam [this message]
2026-03-25 11:57 ` Vladimir Oltean
2026-03-26 8:04 ` Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 11/27] drm/rockchip: dw_hdmi: avoid direct dereference of phy->dev.of_node Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 12/27] usb: host: tegra: " Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 13/27] usb: gadget: tegra-xudc: " Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 14/27] drm/msm/dp: remove debugging prints with internal struct phy state Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 15/27] phy: move provider API out of public <linux/phy/phy.h> Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 16/27] phy: make phy_get_mode(), phy_(get|set)_bus_width() NULL tolerant Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 17/27] phy: introduce phy_get_max_link_rate() helper for consumers Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 18/27] drm/rockchip: dsi: include PHY provider header Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 19/27] drm: bridge: cdns-mhdp8546: use consumer API for getting PHY bus width Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 20/27] media: sunxi: a83-mips-csi2: include PHY provider header Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 21/27] net: renesas: rswitch: " Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 22/27] pinctrl: tegra-xusb: " Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 23/27] power: supply: cpcap-charger: include missing <linux/property.h> Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 24/27] phy: include PHY provider header (1/2) Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 25/27] phy: include PHY provider header (2/2) Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 26/27] phy: remove temporary provider compatibility from consumer header Vladimir Oltean
2026-03-19 22:32 ` [PATCH v5 phy-next 27/27] MAINTAINERS: add regexes for linux-phy Vladimir Oltean
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