linux-kernel - RE: [PATCH 1/3] drm/radeon: Use RMW accessors for changing LNKCTL2

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Date: Thu, 15 Feb 2024 17:32:16 +0000
From: "Deucher, Alexander" <Alexander.Deucher@....com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	"amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>, Daniel
 Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>, Dennis
 Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, Jason
 Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>, "Pan, Xinhui"
	<Xinhui.Pan@....com>, "Koenig, Christian" <Christian.Koenig@....com>
CC: Lukas Wunner <lukas@...ner.de>
Subject: RE: [PATCH 1/3] drm/radeon: Use RMW accessors for changing LNKCTL2

[Public]

> -----Original Message-----
> From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Sent: Thursday, February 15, 2024 8:32 AM
> To: Deucher, Alexander <Alexander.Deucher@....com>; amd-
> gfx@...ts.freedesktop.org; Daniel Vetter <daniel@...ll.ch>; David Airlie
> <airlied@...il.com>; Dennis Dalessandro
> <dennis.dalessandro@...nelisnetworks.com>; dri-
> devel@...ts.freedesktop.org; Jason Gunthorpe <jgg@...pe.ca>; Leon
> Romanovsky <leon@...nel.org>; linux-kernel@...r.kernel.org; linux-
> rdma@...r.kernel.org; Pan, Xinhui <Xinhui.Pan@....com>; Koenig, Christian
> <Christian.Koenig@....com>
> Cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>; Lukas Wunner
> <lukas@...ner.de>
> Subject: [PATCH 1/3] drm/radeon: Use RMW accessors for changing LNKCTL2
>
> Convert open coded RMW accesses for LNKCTL2 to use
> pcie_capability_clear_and_set_word() which makes its easier to understand
> what the code tries to do.
>
> LNKCTL2 is not really owned by any driver because it is a collection of control
> bits that PCI core might need to touch. RMW accessors already have support
> for proper locking for a selected set of registers
> (LNKCTL2 is not yet among them but likely will be in the future) to avoid losing
> concurrent updates.
>
> Suggested-by: Lukas Wunner <lukas@...ner.de>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

The radeon and amdgpu patches are:
Acked-by: Alex Deucher <alexander.deucher@....com>

Are you looking for me to pick them up or do you want to land them as part of some larger change?  Either way is fine with me.

Alex

> ---
>  drivers/gpu/drm/radeon/cik.c | 40 ++++++++++++++----------------------
>  drivers/gpu/drm/radeon/si.c  | 40 ++++++++++++++----------------------
>  2 files changed, 30 insertions(+), 50 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/cik.c b/drivers/gpu/drm/radeon/cik.c
> index 10be30366c2b..b5e96a8fc2c1 100644
> --- a/drivers/gpu/drm/radeon/cik.c
> +++ b/drivers/gpu/drm/radeon/cik.c
> @@ -9592,28 +9592,18 @@ static void cik_pcie_gen3_enable(struct
> radeon_device *rdev)
>
> PCI_EXP_LNKCTL_HAWD);
>
>                               /* linkctl2 */
> -                             pcie_capability_read_word(root,
> PCI_EXP_LNKCTL2,
> -                                                       &tmp16);
> -                             tmp16 &= ~(PCI_EXP_LNKCTL2_ENTER_COMP
> |
> -                                        PCI_EXP_LNKCTL2_TX_MARGIN);
> -                             tmp16 |= (bridge_cfg2 &
> -                                       (PCI_EXP_LNKCTL2_ENTER_COMP |
> -                                        PCI_EXP_LNKCTL2_TX_MARGIN));
> -                             pcie_capability_write_word(root,
> -                                                        PCI_EXP_LNKCTL2,
> -                                                        tmp16);
> -
> -                             pcie_capability_read_word(rdev->pdev,
> -                                                       PCI_EXP_LNKCTL2,
> -                                                       &tmp16);
> -                             tmp16 &= ~(PCI_EXP_LNKCTL2_ENTER_COMP
> |
> -                                        PCI_EXP_LNKCTL2_TX_MARGIN);
> -                             tmp16 |= (gpu_cfg2 &
> -                                       (PCI_EXP_LNKCTL2_ENTER_COMP |
> -                                        PCI_EXP_LNKCTL2_TX_MARGIN));
> -                             pcie_capability_write_word(rdev->pdev,
> -                                                        PCI_EXP_LNKCTL2,
> -                                                        tmp16);
> +                             pcie_capability_clear_and_set_word(root,
> PCI_EXP_LNKCTL2,
> +
> PCI_EXP_LNKCTL2_ENTER_COMP |
> +
> PCI_EXP_LNKCTL2_TX_MARGIN,
> +                                                                bridge_cfg2
> |
> +
> (PCI_EXP_LNKCTL2_ENTER_COMP |
> +
> PCI_EXP_LNKCTL2_TX_MARGIN));
> +                             pcie_capability_clear_and_set_word(rdev-
> >pdev, PCI_EXP_LNKCTL2,
> +
> PCI_EXP_LNKCTL2_ENTER_COMP |
> +
> PCI_EXP_LNKCTL2_TX_MARGIN,
> +                                                                gpu_cfg2 |
> +
> (PCI_EXP_LNKCTL2_ENTER_COMP |
> +
> PCI_EXP_LNKCTL2_TX_MARGIN));
>
>                               tmp = RREG32_PCIE_PORT(PCIE_LC_CNTL4);
>                               tmp &= ~LC_SET_QUIESCE;
> @@ -9627,15 +9617,15 @@ static void cik_pcie_gen3_enable(struct
> radeon_device *rdev)
>       speed_cntl &= ~LC_FORCE_DIS_SW_SPEED_CHANGE;
>       WREG32_PCIE_PORT(PCIE_LC_SPEED_CNTL, speed_cntl);
>
> -     pcie_capability_read_word(rdev->pdev, PCI_EXP_LNKCTL2, &tmp16);
> -     tmp16 &= ~PCI_EXP_LNKCTL2_TLS;
> +     tmp16 = 0;
>       if (speed_cap == PCIE_SPEED_8_0GT)
>               tmp16 |= PCI_EXP_LNKCTL2_TLS_8_0GT; /* gen3 */
>       else if (speed_cap == PCIE_SPEED_5_0GT)
>               tmp16 |= PCI_EXP_LNKCTL2_TLS_5_0GT; /* gen2 */
>       else
>               tmp16 |= PCI_EXP_LNKCTL2_TLS_2_5GT; /* gen1 */
> -     pcie_capability_write_word(rdev->pdev, PCI_EXP_LNKCTL2, tmp16);
> +     pcie_capability_clear_and_set_word(rdev->pdev, PCI_EXP_LNKCTL2,
> +                                        PCI_EXP_LNKCTL2_TLS, tmp16);
>
>       speed_cntl = RREG32_PCIE_PORT(PCIE_LC_SPEED_CNTL);
>       speed_cntl |= LC_INITIATE_LINK_SPEED_CHANGE; diff --git
> a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c index
> 85e9cba49cec..8eeaea64c75d 100644
> --- a/drivers/gpu/drm/radeon/si.c
> +++ b/drivers/gpu/drm/radeon/si.c
> @@ -7193,28 +7193,18 @@ static void si_pcie_gen3_enable(struct
> radeon_device *rdev)
>
> PCI_EXP_LNKCTL_HAWD);
>
>                               /* linkctl2 */
> -                             pcie_capability_read_word(root,
> PCI_EXP_LNKCTL2,
> -                                                       &tmp16);
> -                             tmp16 &= ~(PCI_EXP_LNKCTL2_ENTER_COMP
> |
> -                                        PCI_EXP_LNKCTL2_TX_MARGIN);
> -                             tmp16 |= (bridge_cfg2 &
> -                                       (PCI_EXP_LNKCTL2_ENTER_COMP |
> -                                        PCI_EXP_LNKCTL2_TX_MARGIN));
> -                             pcie_capability_write_word(root,
> -                                                        PCI_EXP_LNKCTL2,
> -                                                        tmp16);
> -
> -                             pcie_capability_read_word(rdev->pdev,
> -                                                       PCI_EXP_LNKCTL2,
> -                                                       &tmp16);
> -                             tmp16 &= ~(PCI_EXP_LNKCTL2_ENTER_COMP
> |
> -                                        PCI_EXP_LNKCTL2_TX_MARGIN);
> -                             tmp16 |= (gpu_cfg2 &
> -                                       (PCI_EXP_LNKCTL2_ENTER_COMP |
> -                                        PCI_EXP_LNKCTL2_TX_MARGIN));
> -                             pcie_capability_write_word(rdev->pdev,
> -                                                        PCI_EXP_LNKCTL2,
> -                                                        tmp16);
> +                             pcie_capability_clear_and_set_word(root,
> PCI_EXP_LNKCTL2,
> +
> PCI_EXP_LNKCTL2_ENTER_COMP |
> +
> PCI_EXP_LNKCTL2_TX_MARGIN,
> +                                                                bridge_cfg2
> &
> +
> (PCI_EXP_LNKCTL2_ENTER_COMP |
> +
> PCI_EXP_LNKCTL2_TX_MARGIN));
> +                             pcie_capability_clear_and_set_word(rdev-
> >pdev, PCI_EXP_LNKCTL2,
> +
> PCI_EXP_LNKCTL2_ENTER_COMP |
> +
> PCI_EXP_LNKCTL2_TX_MARGIN,
> +                                                                gpu_cfg2 &
> +
> (PCI_EXP_LNKCTL2_ENTER_COMP |
> +
> PCI_EXP_LNKCTL2_TX_MARGIN));
>
>                               tmp = RREG32_PCIE_PORT(PCIE_LC_CNTL4);
>                               tmp &= ~LC_SET_QUIESCE;
> @@ -7228,15 +7218,15 @@ static void si_pcie_gen3_enable(struct
> radeon_device *rdev)
>       speed_cntl &= ~LC_FORCE_DIS_SW_SPEED_CHANGE;
>       WREG32_PCIE_PORT(PCIE_LC_SPEED_CNTL, speed_cntl);
>
> -     pcie_capability_read_word(rdev->pdev, PCI_EXP_LNKCTL2, &tmp16);
> -     tmp16 &= ~PCI_EXP_LNKCTL2_TLS;
> +     tmp16 = 0;
>       if (speed_cap == PCIE_SPEED_8_0GT)
>               tmp16 |= PCI_EXP_LNKCTL2_TLS_8_0GT; /* gen3 */
>       else if (speed_cap == PCIE_SPEED_5_0GT)
>               tmp16 |= PCI_EXP_LNKCTL2_TLS_5_0GT; /* gen2 */
>       else
>               tmp16 |= PCI_EXP_LNKCTL2_TLS_2_5GT; /* gen1 */
> -     pcie_capability_write_word(rdev->pdev, PCI_EXP_LNKCTL2, tmp16);
> +     pcie_capability_clear_and_set_word(rdev->pdev, PCI_EXP_LNKCTL2,
> +                                        PCI_EXP_LNKCTL2_TLS, tmp16);
>
>       speed_cntl = RREG32_PCIE_PORT(PCIE_LC_SPEED_CNTL);
>       speed_cntl |= LC_INITIATE_LINK_SPEED_CHANGE;
> --
> 2.39.2