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Mon, 08 Nov 2021 17:01:49 -0800 (PST) MIME-Version: 1.0 References: <20211102161125.1144023-1-kernel@esmil.dk> <20211102161125.1144023-13-kernel@esmil.dk> In-Reply-To: From: Linus Walleij Date: Tue, 9 Nov 2021 02:01:37 +0100 Message-ID: Subject: Re: [PATCH v3 12/16] pinctrl: starfive: Add pinctrl driver for StarFive SoCs To: Andy Shevchenko Cc: Emil Renner Berthing , linux-riscv , devicetree , linux-clk , "open list:GPIO SUBSYSTEM" , "open list:SERIAL DRIVERS" , Palmer Dabbelt , Paul Walmsley , Rob Herring , Michael Turquette , Stephen Boyd , Thomas Gleixner , Marc Zyngier , Philipp Zabel , Greg Kroah-Hartman , Daniel Lezcano , Andy Shevchenko , Jiri Slaby , Maximilian Luz , Sagar Kadam , Drew Fustini , Geert Uytterhoeven , Michael Zhu , Fu Wei , Anup Patel , Atish Patra , Matteo Croce , Linux Kernel Mailing List , Huan Feng Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 2, 2021 at 9:08 PM Andy Shevchenko wrote: (...) > > On Tue, Nov 2, 2021 at 6:50 PM Emil Renner Berthing wrote: > > ... > > > > +static int starfive_pinconf_group_set(struct pinctrl_dev *pctldev, > > > + unsigned int gsel, > > > + unsigned long *configs, > > > + unsigned int num_configs) > > > +{ > > > + struct starfive_pinctrl *sfp = pinctrl_dev_get_drvdata(pctldev); > > > + const struct group_desc *group; > > > + u16 mask, value; > > > + int i; > > > + > > > + group = pinctrl_generic_get_group(pctldev, gsel); > > > + if (!group) > > > + return -EINVAL; > > > + > > > + mask = 0; > > > + value = 0; > > > + for (i = 0; i < num_configs; i++) { > > > + int param = pinconf_to_config_param(configs[i]); > > > + u32 arg = pinconf_to_config_argument(configs[i]); > > > + > > > + switch (param) { > > > + case PIN_CONFIG_BIAS_DISABLE: > > > + mask |= PAD_BIAS_MASK; > > > + value = (value & ~PAD_BIAS_MASK) | PAD_BIAS_DISABLE; > > > + break; > > > + case PIN_CONFIG_BIAS_PULL_DOWN: > > > + if (arg == 0) > > > + return -ENOTSUPP; > > > + mask |= PAD_BIAS_MASK; > > > + value = (value & ~PAD_BIAS_MASK) | PAD_BIAS_PULL_DOWN; > > > + break; > > > + case PIN_CONFIG_BIAS_PULL_UP: > > > + if (arg == 0) > > > + return -ENOTSUPP; > > > + mask |= PAD_BIAS_MASK; > > > + value = value & ~PAD_BIAS_MASK; > > > + break; > > > + case PIN_CONFIG_DRIVE_STRENGTH: > > > + mask |= PAD_DRIVE_STRENGTH_MASK; > > > + value = (value & ~PAD_DRIVE_STRENGTH_MASK) | > > > + starfive_drive_strength_from_max_mA(arg); > > > + break; > > > + case PIN_CONFIG_INPUT_ENABLE: > > > + mask |= PAD_INPUT_ENABLE; > > > + if (arg) > > > + value |= PAD_INPUT_ENABLE; > > > + else > > > + value &= ~PAD_INPUT_ENABLE; > > > + break; > > > + case PIN_CONFIG_INPUT_SCHMITT_ENABLE: > > > + mask |= PAD_INPUT_SCHMITT_ENABLE; > > > + if (arg) > > > + value |= PAD_INPUT_SCHMITT_ENABLE; > > > + else > > > + value &= ~PAD_INPUT_SCHMITT_ENABLE; > > > + break; > > > + case PIN_CONFIG_SLEW_RATE: > > > + mask |= PAD_SLEW_RATE_MASK; > > > + value = (value & ~PAD_SLEW_RATE_MASK) | > > > + ((arg << PAD_SLEW_RATE_POS) & PAD_SLEW_RATE_MASK); > > > + break; > > > + case PIN_CONFIG_STARFIVE_STRONG_PULL_UP: > > > + if (arg) { > > > + mask |= PAD_BIAS_MASK; > > > + value = (value & ~PAD_BIAS_MASK) | > > > + PAD_BIAS_STRONG_PULL_UP; > > > + } else { > > > + mask |= PAD_BIAS_STRONG_PULL_UP; > > > + value = value & ~PAD_BIAS_STRONG_PULL_UP; > > > + } > > > + break; > > > + default: > > > + return -ENOTSUPP; > > > + } > > > + } > > > + > > > + for (i = 0; i < group->num_pins; i++) > > > + starfive_padctl_rmw(sfp, group->pins[i], mask, value); > > > + > > > + return 0; > > > +} > > Linus any comments on this code (sorry if I missed your reply)? The > idea behind above is to skip all settings from the same category and > apply only the last one, e.g. if we have "bias set to X", ..., "bias > disable", ..., "bias set to Y", the hardware will see only the last > operation, i.e. "bias set to Y". I think it may not be the best > approach (theoretically?) since the hardware definitely may behave > differently on the other side in case of such series of the > configurations (yes, I have seen some interesting implementations of > the touchpad / touchscreen GPIOs that may be affected). That sounds weird. I think we need to look at how other drivers deal with this. To me it seems more natural that starfive_padctl_rmw(sfp, group->pins[i], mask, value); would get called at the end of each iteration of the for (i = 0; i < num_configs; i++) loop. Yours, Linus Walleij