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Message-ID: <e252f15f-ea80-4969-b754-82da5f9a7f56@wanadoo.fr> Date: Wed, 11 Jun 2025 22:16:52 +0900 From: Vincent Mailhol <mailhol.vincent@...adoo.fr> To: Bartosz Golaszewski <brgl@...ev.pl> Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, linux-can@...r.kernel.org, linux-arm-msm@...r.kernel.org, Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, Andrew Lunn <andrew@...n.ch>, Vladimir Oltean <olteanv@...il.com>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Linus Walleij <linus.walleij@...aro.org>, "Chester A. Unal" <chester.a.unal@...nc9.com>, Daniel Golle <daniel@...rotopia.org>, DENG Qingfang <dqfext@...il.com>, Sean Wang <sean.wang@...iatek.com>, Matthias Brugger <matthias.bgg@...il.com>, AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, Marc Kleine-Budde <mkl@...gutronix.de>, Heiner Kallweit <hkallweit1@...il.com>, Russell King <linux@...linux.org.uk> Subject: Re: [PATCH 3/4] net: can: mcp251x: use new GPIO line value setter callbacks On 11/06/2025 at 01:05, Bartosz Golaszewski wrote: > On Tue, Jun 10, 2025 at 5:48 PM Vincent Mailhol > <mailhol.vincent@...adoo.fr> wrote: >> >> On 10/06/2025 at 23:05, Bartosz Golaszewski wrote: >>> On Tue, Jun 10, 2025 at 3:55 PM Vincent Mailhol >>> <mailhol.vincent@...adoo.fr> wrote: >>>> >>>> On 10/06/2025 at 21:37, Bartosz Golaszewski wrote: >>>>> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org> >>>>> >>>>> struct gpio_chip now has callbacks for setting line values that return >>>>> an integer, allowing to indicate failures. Convert the driver to using >>>>> them. >>>>> >>>>> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org> >>>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >>>> >>>> This does not match the address with which you sent the patch: brgl@...ev.pl >>>> >>>>> --- >>>>> drivers/net/can/spi/mcp251x.c | 16 ++++++++++------ >>>>> 1 file changed, 10 insertions(+), 6 deletions(-) >>>>> >>>>> diff --git a/drivers/net/can/spi/mcp251x.c b/drivers/net/can/spi/mcp251x.c >>>>> index ec5c64006a16f703bc816983765584c5f3ac76e8..7545497d14b46c6388f3976c2bf7b9a99e959c1e 100644 >>>>> --- a/drivers/net/can/spi/mcp251x.c >>>>> +++ b/drivers/net/can/spi/mcp251x.c >>>>> @@ -530,8 +530,8 @@ static int mcp251x_gpio_get_multiple(struct gpio_chip *chip, >>>>> return 0; >>>>> } >>>>> >>>>> -static void mcp251x_gpio_set(struct gpio_chip *chip, unsigned int offset, >>>>> - int value) >>>>> +static int mcp251x_gpio_set(struct gpio_chip *chip, unsigned int offset, >>>>> + int value) >>>>> { >>>>> struct mcp251x_priv *priv = gpiochip_get_data(chip); >>>>> u8 mask, val; >>>>> @@ -545,9 +545,11 @@ static void mcp251x_gpio_set(struct gpio_chip *chip, unsigned int offset, >>>>> >>>>> priv->reg_bfpctrl &= ~mask; >>>>> priv->reg_bfpctrl |= val; >>>>> + >>>>> + return 0; >>>> >>>> mcp251x_gpio_set() calls mcp251x_write_bits() which calls mcp251x_spi_write() >>>> which can fail. >>>> >>>> For this change to really make sense, the return value of mcp251x_spi_write() >>>> should be propagated all the way around. >>>> >>> >>> I don't know this code so I followed the example of the rest of the >>> codebase where the result of this function is never checked - even in >>> functions that do return values. I didn't know the reason for this and >>> so didn't want to break anything as I have no means of testing it. >> >> The return value of mcp251x_spi_write() is used in mcp251x_hw_reset(). In other >> locations, mcp251x_spi_write() is only used in functions which return void, so >> obviously, the return value is not checked. >> > > Wait, after a second look GPIO callbacks (including those that return > a value like request()) use mcp251x_write_bits() which has no return > value. Yes. Read again my first message: mcp251x_gpio_set() calls mcp251x_write_bits() which calls mcp251x_spi_write() which can fail. My point is that the grand father can fail. > It probably should propagate what mcp251x_spi_write() returns Exactly what I asked for :) > but that's material for a different series. Why? Are you going to do this other series? If the answer is no, then please just do it here. Propagating the error in mcp251x_write_bits() is a three line change. Am I asking for too much? > The goal of this one is to > use the new setters treewide and drop the old ones from struct > gpio_chip. Yours sincerely, Vincent Mailhol
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