From: "Ivan T . Ivanov" <iivanov@suse.de> To: Florian Fainelli <f.fainelli@gmail.com>, Ray Jui <rjui@broadcom.com>, Scott Branden <sbranden@broadcom.com>, Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Phil Elwell <phil@raspberrypi.org> Subject: Re: [PATCH] i2c: bcm2835: Set clock-stretch timeout to 35ms Date: Fri, 28 Jan 2022 10:47:17 +0200 [thread overview] Message-ID: <20220128084717.rbvbciprfqen4rvb@suse> (raw) In-Reply-To: <20220117102504.90585-1-iivanov@suse.de> On 01-17 11:25, Ivan T. Ivanov wrote: > Date: Mon, 17 Jan 2022 11:25:04 +0100 > From: "Ivan T. Ivanov" <iivanov@suse.de> > To: Florian Fainelli <f.fainelli@gmail.com>, Ray Jui <rjui@broadcom.com>, > Scott Branden <sbranden@broadcom.com>, Nicolas Saenz Julienne > <nsaenz@kernel.org> > Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Phil > Elwell <phil@raspberrypi.org>, "Ivan T . Ivanov" <iivanov@suse.de> > Subject: [PATCH] i2c: bcm2835: Set clock-stretch timeout to 35ms > Message-Id: <20220117102504.90585-1-iivanov@suse.de> Tags: all arm i2c linux me ring rpi sent Hi, > > From: Phil Elwell <phil@raspberrypi.org> > > The BCM2835 I2C blocks have a register to set the clock-stretch > timeout - how long the device is allowed to hold SCL low - in bus > cycles. The current driver doesn't write to the register, therefore > the default value of 64 cycles is being used for all devices. > > Set the timeout to the value recommended for SMBus - 35ms. > > See: https://github.com/raspberrypi/linux/issues/3064 It will be nice if we have this fix upstream. Regards, Ivan > > Signed-off-by: Phil Elwell <phil@raspberrypi.org> > [iivanov@suse.de fix small coding style issue] > Signed-off-by: Ivan T. Ivanov <iivanov@suse.de> > --- > drivers/i2c/busses/i2c-bcm2835.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c > index 37443edbf754..9cce0e15da32 100644 > --- a/drivers/i2c/busses/i2c-bcm2835.c > +++ b/drivers/i2c/busses/i2c-bcm2835.c > @@ -106,6 +106,7 @@ static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate, > { > struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw); > u32 redl, fedl; > + u32 clk_tout; > u32 divider = clk_bcm2835_i2c_calc_divider(rate, parent_rate); > > if (divider == -EINVAL) > @@ -129,6 +130,17 @@ static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate, > bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DEL, > (fedl << BCM2835_I2C_FEDL_SHIFT) | > (redl << BCM2835_I2C_REDL_SHIFT)); > + > + /* > + * Set the clock stretch timeout to the SMBUs-recommended 35ms. > + */ > + if (rate > 0xffff * 1000 / 35) > + clk_tout = 0xffff; > + else > + clk_tout = 35 * rate / 1000; > + > + bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_CLKT, clk_tout); > + > return 0; > } > > -- > 2.26.2 >
WARNING: multiple messages have this Message-ID (diff)
From: "Ivan T . Ivanov" <iivanov@suse.de> To: Florian Fainelli <f.fainelli@gmail.com>, Ray Jui <rjui@broadcom.com>, Scott Branden <sbranden@broadcom.com>, Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Phil Elwell <phil@raspberrypi.org> Subject: Re: [PATCH] i2c: bcm2835: Set clock-stretch timeout to 35ms Date: Fri, 28 Jan 2022 10:47:17 +0200 [thread overview] Message-ID: <20220128084717.rbvbciprfqen4rvb@suse> (raw) In-Reply-To: <20220117102504.90585-1-iivanov@suse.de> On 01-17 11:25, Ivan T. Ivanov wrote: > Date: Mon, 17 Jan 2022 11:25:04 +0100 > From: "Ivan T. Ivanov" <iivanov@suse.de> > To: Florian Fainelli <f.fainelli@gmail.com>, Ray Jui <rjui@broadcom.com>, > Scott Branden <sbranden@broadcom.com>, Nicolas Saenz Julienne > <nsaenz@kernel.org> > Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Phil > Elwell <phil@raspberrypi.org>, "Ivan T . Ivanov" <iivanov@suse.de> > Subject: [PATCH] i2c: bcm2835: Set clock-stretch timeout to 35ms > Message-Id: <20220117102504.90585-1-iivanov@suse.de> Tags: all arm i2c linux me ring rpi sent Hi, > > From: Phil Elwell <phil@raspberrypi.org> > > The BCM2835 I2C blocks have a register to set the clock-stretch > timeout - how long the device is allowed to hold SCL low - in bus > cycles. The current driver doesn't write to the register, therefore > the default value of 64 cycles is being used for all devices. > > Set the timeout to the value recommended for SMBus - 35ms. > > See: https://github.com/raspberrypi/linux/issues/3064 It will be nice if we have this fix upstream. Regards, Ivan > > Signed-off-by: Phil Elwell <phil@raspberrypi.org> > [iivanov@suse.de fix small coding style issue] > Signed-off-by: Ivan T. Ivanov <iivanov@suse.de> > --- > drivers/i2c/busses/i2c-bcm2835.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c > index 37443edbf754..9cce0e15da32 100644 > --- a/drivers/i2c/busses/i2c-bcm2835.c > +++ b/drivers/i2c/busses/i2c-bcm2835.c > @@ -106,6 +106,7 @@ static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate, > { > struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw); > u32 redl, fedl; > + u32 clk_tout; > u32 divider = clk_bcm2835_i2c_calc_divider(rate, parent_rate); > > if (divider == -EINVAL) > @@ -129,6 +130,17 @@ static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate, > bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DEL, > (fedl << BCM2835_I2C_FEDL_SHIFT) | > (redl << BCM2835_I2C_REDL_SHIFT)); > + > + /* > + * Set the clock stretch timeout to the SMBUs-recommended 35ms. > + */ > + if (rate > 0xffff * 1000 / 35) > + clk_tout = 0xffff; > + else > + clk_tout = 35 * rate / 1000; > + > + bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_CLKT, clk_tout); > + > return 0; > } > > -- > 2.26.2 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-01-28 8:47 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-01-17 10:25 [PATCH] i2c: bcm2835: Set clock-stretch timeout to 35ms Ivan T. Ivanov 2022-01-17 10:25 ` Ivan T. Ivanov 2022-01-28 8:47 ` Ivan T . Ivanov [this message] 2022-01-28 8:47 ` Ivan T . Ivanov 2022-01-28 10:37 ` Wolfram Sang 2022-01-28 10:37 ` Wolfram Sang 2022-02-07 15:15 ` Wolfram Sang 2022-02-07 15:15 ` Wolfram Sang 2022-02-07 15:41 ` Ivan T. Ivanov 2022-02-07 15:41 ` Ivan T. Ivanov
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20220128084717.rbvbciprfqen4rvb@suse \ --to=iivanov@suse.de \ --cc=f.fainelli@gmail.com \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-i2c@vger.kernel.org \ --cc=nsaenz@kernel.org \ --cc=phil@raspberrypi.org \ --cc=rjui@broadcom.com \ --cc=sbranden@broadcom.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.