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Sat, 02 Nov 2024 10:19:27 -0700 (PDT) Received: from thinkpad ([220.158.156.209]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-720bc1e5722sm4335321b3a.71.2024.11.02.10.19.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 Nov 2024 10:19:27 -0700 (PDT) Date: Sat, 2 Nov 2024 22:49:20 +0530 From: Manivannan Sadhasivam To: AngeloGioacchino Del Regno Cc: linux-pci@vger.kernel.org, ryder.lee@mediatek.com, jianjun.wang@mediatek.com, lpieralisi@kernel.org, kw@linux.com, robh@kernel.org, bhelgaas@google.com, matthias.bgg@gmail.com, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel@collabora.com, fshao@chromium.org Subject: Re: [PATCH v3 1/2] PCI: mediatek-gen3: Add support for setting max-link-speed limit Message-ID: <20241102171920.epjf3j4pkbb5u4xq@thinkpad> References: <20240918081307.51264-1-angelogioacchino.delregno@collabora.com> <20240918081307.51264-2-angelogioacchino.delregno@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240918081307.51264-2-angelogioacchino.delregno@collabora.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241102_101929_397774_05F5E1CE X-CRM114-Status: GOOD ( 29.47 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 18, 2024 at 10:13:06AM +0200, AngeloGioacchino Del Regno wrote: > Add support for respecting the max-link-speed devicetree property, > forcing a maximum speed (Gen) for a PCI-Express port. > > Since the MediaTek PCIe Gen3 controllers also expose the maximum > supported link speed in the PCIE_BASE_CFG register, if property > max-link-speed is specified in devicetree, validate it against the > controller capabilities and proceed setting the limitations only > if the wanted Gen is lower than the maximum one that is supported > by the controller itself (otherwise it makes no sense!). > > Signed-off-by: AngeloGioacchino Del Regno Reviewed-by: Manivannan Sadhasivam - Mani > --- > drivers/pci/controller/pcie-mediatek-gen3.c | 55 ++++++++++++++++++++- > 1 file changed, 53 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c > index 66ce4b5d309b..8d4b045633da 100644 > --- a/drivers/pci/controller/pcie-mediatek-gen3.c > +++ b/drivers/pci/controller/pcie-mediatek-gen3.c > @@ -28,7 +28,11 @@ > > #include "../pci.h" > > +#define PCIE_BASE_CFG_REG 0x14 > +#define PCIE_BASE_CFG_SPEED GENMASK(15, 8) > + > #define PCIE_SETTING_REG 0x80 > +#define PCIE_SETTING_GEN_SUPPORT GENMASK(14, 12) > #define PCIE_PCI_IDS_1 0x9c > #define PCI_CLASS(class) (class << 8) > #define PCIE_RC_MODE BIT(0) > @@ -125,6 +129,9 @@ > > struct mtk_gen3_pcie; > > +#define PCIE_CONF_LINK2_CTL_STS 0x10b0 > +#define PCIE_CONF_LINK2_LCR2_LINK_SPEED GENMASK(3, 0) > + > /** > * struct mtk_gen3_pcie_pdata - differentiate between host generations > * @power_up: pcie power_up callback > @@ -160,6 +167,7 @@ struct mtk_msi_set { > * @phy: PHY controller block > * @clks: PCIe clocks > * @num_clks: PCIe clocks count for this port > + * @max_link_speed: Maximum link speed (PCIe Gen) for this port > * @irq: PCIe controller interrupt number > * @saved_irq_state: IRQ enable state saved at suspend time > * @irq_lock: lock protecting IRQ register access > @@ -180,6 +188,7 @@ struct mtk_gen3_pcie { > struct phy *phy; > struct clk_bulk_data *clks; > int num_clks; > + u8 max_link_speed; > > int irq; > u32 saved_irq_state; > @@ -381,11 +390,27 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie) > int err; > u32 val; > > - /* Set as RC mode */ > + /* Set as RC mode and set controller PCIe Gen speed restriction, if any */ > val = readl_relaxed(pcie->base + PCIE_SETTING_REG); > val |= PCIE_RC_MODE; > + if (pcie->max_link_speed) { > + val &= ~PCIE_SETTING_GEN_SUPPORT; > + > + /* Can enable link speed support only from Gen2 onwards */ > + if (pcie->max_link_speed >= 2) > + val |= FIELD_PREP(PCIE_SETTING_GEN_SUPPORT, > + GENMASK(pcie->max_link_speed - 2, 0)); > + } > writel_relaxed(val, pcie->base + PCIE_SETTING_REG); > > + /* Set Link Control 2 (LNKCTL2) speed restriction, if any */ > + if (pcie->max_link_speed) { > + val = readl_relaxed(pcie->base + PCIE_CONF_LINK2_CTL_STS); > + val &= ~PCIE_CONF_LINK2_LCR2_LINK_SPEED; > + val |= FIELD_PREP(PCIE_CONF_LINK2_LCR2_LINK_SPEED, pcie->max_link_speed); > + writel_relaxed(val, pcie->base + PCIE_CONF_LINK2_CTL_STS); > + } > + > /* Set class code */ > val = readl_relaxed(pcie->base + PCIE_PCI_IDS_1); > val &= ~GENMASK(31, 8); > @@ -1004,9 +1029,21 @@ static void mtk_pcie_power_down(struct mtk_gen3_pcie *pcie) > reset_control_bulk_assert(pcie->soc->phy_resets.num_resets, pcie->phy_resets); > } > > +static int mtk_pcie_get_controller_max_link_speed(struct mtk_gen3_pcie *pcie) > +{ > + u32 val; > + int ret; > + > + val = readl_relaxed(pcie->base + PCIE_BASE_CFG_REG); > + val = FIELD_GET(PCIE_BASE_CFG_SPEED, val); > + ret = fls(val); > + > + return ret > 0 ? ret : -EINVAL; > +} > + > static int mtk_pcie_setup(struct mtk_gen3_pcie *pcie) > { > - int err; > + int err, max_speed; > > err = mtk_pcie_parse_port(pcie); > if (err) > @@ -1031,6 +1068,20 @@ static int mtk_pcie_setup(struct mtk_gen3_pcie *pcie) > if (err) > return err; > > + err = of_pci_get_max_link_speed(pcie->dev->of_node); > + if (err > 0) { > + /* Get the maximum speed supported by the controller */ > + max_speed = mtk_pcie_get_controller_max_link_speed(pcie); > + > + /* Set max_link_speed only if the controller supports it */ > + if (max_speed >= 0 && max_speed <= err) { > + pcie->max_link_speed = err; > + dev_dbg(pcie->dev, > + "Max controller link speed Gen%d, override to Gen%u", > + max_speed, pcie->max_link_speed); > + } > + } > + > /* Try link up */ > err = mtk_pcie_startup_port(pcie); > if (err) > -- > 2.46.0 > > -- மணிவண்ணன் சதாசிவம்