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([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id ix22-20020a170902f81600b001c735421215sm4424645plb.216.2023.11.09.21.24.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Nov 2023 21:24:34 -0800 (PST) Sender: Guenter Roeck Message-ID: Date: Thu, 9 Nov 2023 21:24:32 -0800 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] watchdog: mediatek: mt7988: add wdt support Content-Language: en-US To: Daniel Golle , Wim Van Sebroeck , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Matthias Brugger , AngeloGioacchino Del Regno , Philipp Zabel , linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org References: <6912f6f406bc45674020681184f3eeca2f2cb63f.1699576174.git.daniel@makrotopia.org> From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/9/23 16:30, Daniel Golle wrote: > Add support for watchdog and reset generator unit of the MediaTek > MT7988 SoC. > > Signed-off-by: Daniel Golle > --- > drivers/watchdog/mtk_wdt.c | 56 +++++++++++++++++++++++++++++++++++++- > 1 file changed, 55 insertions(+), 1 deletion(-) > > diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c > index b2330b16b497a..b98b8c29735aa 100644 > --- a/drivers/watchdog/mtk_wdt.c > +++ b/drivers/watchdog/mtk_wdt.c > @@ -12,6 +12,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -58,6 +59,8 @@ > #define WDT_SWSYSRST 0x18U > #define WDT_SWSYS_RST_KEY 0x88000000 > > +#define WDT_SWSYSRST_EN 0xfc > + > #define DRV_NAME "mtk-wdt" > #define DRV_VERSION "1.0" > > @@ -71,44 +74,85 @@ struct mtk_wdt_dev { > struct reset_controller_dev rcdev; > bool disable_wdt_extrst; > bool reset_by_toprgu; > + bool has_swsysrst_en; > }; > > struct mtk_wdt_data { > int toprgu_sw_rst_num; > + bool has_swsysrst_en; > }; > > static const struct mtk_wdt_data mt2712_data = { > .toprgu_sw_rst_num = MT2712_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = false, Those assignments to false, just like assignments to 0, are unnecessary for static variables. > }; > > static const struct mtk_wdt_data mt6795_data = { > .toprgu_sw_rst_num = MT6795_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = false, > }; > > static const struct mtk_wdt_data mt7986_data = { > .toprgu_sw_rst_num = MT7986_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = false, > +}; > + > +static const struct mtk_wdt_data mt7988_data = { > + .toprgu_sw_rst_num = MT7988_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = true, > }; > > static const struct mtk_wdt_data mt8183_data = { > .toprgu_sw_rst_num = MT8183_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = false, > }; > > static const struct mtk_wdt_data mt8186_data = { > .toprgu_sw_rst_num = MT8186_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = false, > }; > > static const struct mtk_wdt_data mt8188_data = { > .toprgu_sw_rst_num = MT8188_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = false, > }; > > static const struct mtk_wdt_data mt8192_data = { > .toprgu_sw_rst_num = MT8192_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = false, > }; > > static const struct mtk_wdt_data mt8195_data = { > .toprgu_sw_rst_num = MT8195_TOPRGU_SW_RST_NUM, > + .has_swsysrst_en = false, > }; > > +static int toprgu_reset_sw_enable(struct reset_controller_dev *rcdev, > + unsigned long id, bool enable) This function name is a bit misleading. It doesn't always _enable_ something, it updates it based on the enable parameter. > +{ > + unsigned int tmp; > + unsigned long flags; > + struct mtk_wdt_dev *data = > + container_of(rcdev, struct mtk_wdt_dev, rcdev); > + > + if (!data->has_swsysrst_en) > + return 0; > + > + spin_lock_irqsave(&data->lock, flags); > + > + tmp = readl(data->wdt_base + WDT_SWSYSRST_EN); > + if (enable) > + tmp |= BIT(id); > + else > + tmp &= ~BIT(id); > + > + writel(tmp, data->wdt_base + WDT_SWSYSRST_EN); > + > + spin_unlock_irqrestore(&data->lock, flags); > + I find this code quite confusing. If it is really necessary to set both WDT_SWSYSRST_EN and WDT_SWSYSRST together, what is the point of locking twice ? Why not just handle this in toprgu_reset_update() while the lock is alread held ? There is a lot of code duplication and inefficiency between toprgu_reset_sw_enable() and toprgu_reset_update(), and I really don't see the value of it if WDT_SWSYSRST_EN and WDT_SWSYSRST have to be written together anyway. > + return 0; This function always returns 0. That does not add any value. > +} > + > static int toprgu_reset_update(struct reset_controller_dev *rcdev, > unsigned long id, bool assert) > { > @@ -135,13 +179,20 @@ static int toprgu_reset_update(struct reset_controller_dev *rcdev, > static int toprgu_reset_assert(struct reset_controller_dev *rcdev, > unsigned long id) > { > + int ret; > + > + ret = toprgu_reset_sw_enable(rcdev, id, true); > + if (ret) > + return ret; > + I am kind of missing the point of this return value check. I guess it is in line with the other unnecessary return values / return value checks in this code, but this really gets a bit out of control. It kind of creates the wrong assumption or expectation that the called code _may_ return an error, but in reality it doesn't. > return toprgu_reset_update(rcdev, id, true); > } > > static int toprgu_reset_deassert(struct reset_controller_dev *rcdev, > unsigned long id) > { > - return toprgu_reset_update(rcdev, id, false); > + toprgu_reset_update(rcdev, id, false); In a way it is commendable that the unnecessary return value handling was dropped, but that makes the code inconsistent with the reset_assert() function. Also, it is inconsistent to have the unnecessary return value check in toprgu_reset_assert() but not here. > + return toprgu_reset_sw_enable(rcdev, id, false); > } > > static int toprgu_reset(struct reset_controller_dev *rcdev, > @@ -406,6 +457,8 @@ static int mtk_wdt_probe(struct platform_device *pdev) > wdt_data->toprgu_sw_rst_num); > if (err) > return err; > + > + mtk_wdt->has_swsysrst_en = wdt_data->has_swsysrst_en; This is too late. The reset controller is already registered here, and the reset controller functions may already have been called. > } > > mtk_wdt->disable_wdt_extrst = Oh well, this and the next property are also called too late because they affect watchdog operation and the watchdog device has already been registered, but that is a different bug and not a reason to add even more race conditions to the driver. > @@ -444,6 +497,7 @@ static const struct of_device_id mtk_wdt_dt_ids[] = { > { .compatible = "mediatek,mt6589-wdt" }, > { .compatible = "mediatek,mt6795-wdt", .data = &mt6795_data }, > { .compatible = "mediatek,mt7986-wdt", .data = &mt7986_data }, > + { .compatible = "mediatek,mt7988-wdt", .data = &mt7988_data }, > { .compatible = "mediatek,mt8183-wdt", .data = &mt8183_data }, > { .compatible = "mediatek,mt8186-wdt", .data = &mt8186_data }, > { .compatible = "mediatek,mt8188-wdt", .data = &mt8188_data },