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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hYtEE-0000vD-Eg; Thu, 06 Jun 2019 14:18:54 +0000 Received: from bhuna.collabora.co.uk ([46.235.227.227]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hYtEA-0000uA-Ff for linux-i3c@lists.infradead.org; Thu, 06 Jun 2019 14:18:52 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id CE789284BB4; Thu, 6 Jun 2019 15:18:47 +0100 (BST) Date: Thu, 6 Jun 2019 16:18:44 +0200 From: Boris Brezillon To: Vitor Soares Subject: Re: [PATCH v2 1/3] i3c: fix i2c and i3c scl rate by bus mode Message-ID: <20190606161844.4a6b759c@collabora.com> In-Reply-To: <47de89f2335930df0ed6903be9afe6de4f46e503.1559821228.git.vitor.soares@synopsys.com> References: <47de89f2335930df0ed6903be9afe6de4f46e503.1559821228.git.vitor.soares@synopsys.com> Organization: Collabora X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190606_071850_789424_868DEA76 X-CRM114-Status: GOOD ( 19.85 ) X-BeenThere: linux-i3c@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Linux I3C List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-i3c@lists.infradead.org, Joao.Pinto@synopsys.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Boris Brezillon Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-i3c" Errors-To: linux-i3c-bounces+linux-i3c=archiver.kernel.org@lists.infradead.org On Thu, 6 Jun 2019 16:00:01 +0200 Vitor Soares wrote: > Currently the I3C framework limits SCL frequency to FM speed when > dealing with a mixed slow bus, even if all I2C devices are FM+ capable. > > The core was also not accounting for I3C speed limitations when > operating in mixed slow mode and was erroneously using FM+ speed as the > max I2C speed when operating in mixed fast mode. > > Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure") > Signed-off-by: Vitor Soares > Cc: Boris Brezillon > Cc: > Cc: > --- > Changes in v2: > Enhance commit message > Add dev_warn() in case user-defined i2c rate doesn't match LVR constraint > Add dev_warn() in case user-defined i3c rate lower than i2c rate. > > drivers/i3c/master.c | 61 +++++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 48 insertions(+), 13 deletions(-) > > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c > index 5f4bd52..8cd5824 100644 > --- a/drivers/i3c/master.c > +++ b/drivers/i3c/master.c > @@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus) > up_read(&bus->lock); > } > > +static struct i3c_master_controller * > +i3c_bus_to_i3c_master(struct i3c_bus *i3cbus) > +{ > + return container_of(i3cbus, struct i3c_master_controller, bus); > +} > + > static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev) > { > return container_of(dev, struct i3c_master_controller, dev); > @@ -565,20 +571,48 @@ static const struct device_type i3c_masterdev_type = { > .groups = i3c_masterdev_groups, > }; > > -int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode) > +int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode, > + unsigned long max_i2c_scl_rate) > { > - i3cbus->mode = mode; > > - if (!i3cbus->scl_rate.i3c) > - i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE; > + struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus); > > - if (!i3cbus->scl_rate.i2c) { > - if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW) > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE; > - else > - i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE; > + i3cbus->mode = mode; > + > + switch (i3cbus->mode) { > + case I3C_BUS_MODE_PURE: > + if (!i3cbus->scl_rate.i3c) > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE; > + break; > + case I3C_BUS_MODE_MIXED_FAST: > + if (!i3cbus->scl_rate.i3c) > + i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE; > + if (!i3cbus->scl_rate.i2c) > + i3cbus->scl_rate.i2c = max_i2c_scl_rate; > + break; > + case I3C_BUS_MODE_MIXED_SLOW: > + if (!i3cbus->scl_rate.i2c) > + i3cbus->scl_rate.i2c = max_i2c_scl_rate; > + if (!i3cbus->scl_rate.i3c || > + i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c) > + i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c; > + break; > + default: > + return -EINVAL; > } > > + if (i3cbus->scl_rate.i3c < i3cbus->scl_rate.i2c) > + dev_warn(&master->dev, > + "i3c-scl-hz=%ld lower than i2c-scl-hz=%ld\n", > + i3cbus->scl_rate.i3c, i3cbus->scl_rate.i2c); > + > + if (i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_SCL_RATE && > + i3cbus->scl_rate.i2c != I3C_BUS_I2C_FM_PLUS_SCL_RATE && > + i3cbus->mode != I3C_BUS_MODE_PURE) If you are so strict, there's clearly no point exposing an i2c-scl-hz property. I'm still not convinced having an i2c rate that's slower than what the I2C/I3C spec defines as the *typical* rate is a bad thing, just like I'm not convinced having an I3C rate that's slower than the I2C one is a problem (it's definitely a weird situation, but there's nothing preventing that in the spec). > + dev_warn(&master->dev, > + "i2c-scl-hz=%ld not defined according MIPI I3C spec\n" > + , i3cbus->scl_rate.i2c); The comma should be on the previous line. > + > /* > * I3C/I2C frequency may have been overridden, check that user-provided > * values are not exceeding max possible frequency. > @@ -1966,9 +2000,6 @@ of_i3c_master_add_i2c_boardinfo(struct i3c_master_controller *master, > /* LVR is encoded in reg[2]. */ > boardinfo->lvr = reg[2]; > > - if (boardinfo->lvr & I3C_LVR_I2C_FM_MODE) > - master->bus.scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE; > - > list_add_tail(&boardinfo->node, &master->boardinfo.i2c); > of_node_get(node); > > @@ -2417,6 +2448,7 @@ int i3c_master_register(struct i3c_master_controller *master, > const struct i3c_master_controller_ops *ops, > bool secondary) > { > + unsigned long i2c_scl_rate = I3C_BUS_I2C_FM_PLUS_SCL_RATE; > struct i3c_bus *i3cbus = i3c_master_get_bus(master); > enum i3c_bus_mode mode = I3C_BUS_MODE_PURE; > struct i2c_dev_boardinfo *i2cbi; > @@ -2466,9 +2498,12 @@ int i3c_master_register(struct i3c_master_controller *master, > ret = -EINVAL; > goto err_put_dev; > } > + > + if (i2cbi->lvr & I3C_LVR_I2C_FM_MODE) > + i2c_scl_rate = I3C_BUS_I2C_FM_SCL_RATE; > } > > - ret = i3c_bus_set_mode(i3cbus, mode); > + ret = i3c_bus_set_mode(i3cbus, mode, i2c_scl_rate); > if (ret) > goto err_put_dev; > _______________________________________________ linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c