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[2001:1c00:c1e:bf00:1054:9d19:e0f0:8214]) by smtp.gmail.com with ESMTPSA id lu26sm227422ejb.33.2021.02.24.11.12.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Feb 2021 11:12:32 -0800 (PST) Subject: Re: [PATCH v1 1/1] i2c: cht-wc: Use fwnode for the controller and IRQ domain To: Andy Shevchenko Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210223172231.2224-1-andriy.shevchenko@linux.intel.com> From: Hans de Goede Message-ID: <7e5f8d81-0ee5-b8ad-ed72-06d4677cd8f7@redhat.com> Date: Wed, 24 Feb 2021 20:12:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2/24/21 1:51 PM, Andy Shevchenko wrote: > On Tue, Feb 23, 2021 at 08:25:35PM +0100, Hans de Goede wrote: >> On 2/23/21 6:22 PM, Andy Shevchenko wrote: >>> It's better to describe the I²C controller and associated IRQ domain with >>> fwnode, so they will find their place in the hierarchy in sysfs and also >>> make easier to debug. >>> >>> Signed-off-by: Andy Shevchenko >>> --- >>> >>> Hans, unfortunately I have no device at hand with INT34D3. This is only compile >>> tested in that sense. Also I would like to hear if you like the idea in general. >>> >>> drivers/i2c/busses/i2c-cht-wc.c | 6 ++++-- >>> 1 file changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/i2c/busses/i2c-cht-wc.c b/drivers/i2c/busses/i2c-cht-wc.c >>> index f80d79e973cd..dbf55842b0dc 100644 >>> --- a/drivers/i2c/busses/i2c-cht-wc.c >>> +++ b/drivers/i2c/busses/i2c-cht-wc.c >>> @@ -303,6 +303,7 @@ static struct bq24190_platform_data bq24190_pdata = { >>> static int cht_wc_i2c_adap_i2c_probe(struct platform_device *pdev) >>> { >>> struct intel_soc_pmic *pmic = dev_get_drvdata(pdev->dev.parent); >>> + struct fwnode_handle *fwnode = dev_fwnode(&pdev->dev); >> >> So this will point to the ACPi-companion fwnode of the CHT Whiskey Cove PMIC >> controller. > > Right. > >>> struct cht_wc_i2c_adap *adap; >>> struct i2c_board_info board_info = { >>> .type = "bq24190", >>> @@ -333,6 +334,7 @@ static int cht_wc_i2c_adap_i2c_probe(struct platform_device *pdev) >>> strlcpy(adap->adapter.name, "PMIC I2C Adapter", >>> sizeof(adap->adapter.name)); >>> adap->adapter.dev.parent = &pdev->dev; >>> + set_primary_fwnode(&adap->adapter.dev, fwnode); >> >> So now we have the main PMIC device i2c-client, the platform-device instantiated >> for the MFD-cell for the PMIC's builtin I2C-controller; and the device instantiated >> for the adapter-device all 3 share the same ACPI-companion fwnode. > > Okay, this step in this patch maybe not needed (or should be a separate change, > but I don't see clearly what would be the benefit out of it). > >>> /* Clear and activate i2c-adapter interrupts, disable client IRQ */ >>> adap->old_irq_mask = adap->irq_mask = ~CHT_WC_EXTCHGRIRQ_ADAP_IRQMASK; >>> @@ -350,8 +352,8 @@ static int cht_wc_i2c_adap_i2c_probe(struct platform_device *pdev) >>> return ret; >>> >>> /* Alloc and register client IRQ */ >>> - adap->irq_domain = irq_domain_add_linear(pdev->dev.of_node, 1, >>> - &irq_domain_simple_ops, NULL); >>> + adap->irq_domain = irq_domain_create_linear(fwnode, 1, >>> + &irq_domain_simple_ops, NULL); >> >> Hmm, not sure this is right, admittedly the old code looks weird too, but now we >> are creating a second irq_domain at the same level as the irq_domain created for >> the IRQ-chip part of the PMIC. But this is really more of a child-domain of just >> the I2C-controller MFD-cell. The IRQ-CHIP part of the PMIC has a single IRQ for the >> I2C controller which gets raised both on i2c-transfer completions and when the >> pin on the PMIC which is reserved as input for the IRQ coming out of the charger-chip >> gets triggered. >> >> IOW we have this: >> >> >> PMIC >> | >> ------------------------------ >> | | | | >> IRQ1 IRQ2 IRQ3 I2C-IRQ >> | >> ---------------------------------- >> | | | | >> READIRQ WRIRQ NACKIRQ CLIENT-IRQ >> >> Where READIRQ, WRIRQ and NACKIRQ are directly consumed >> and the CLIENT-IRQ is being represented as a single IRQ on >> a new irqchip so that we can pass it along to the i2c-driver >> for the charger-chip which is connected to the Whiskey Cove's >> builtin I2C controller. >> >> But doing as you suggest would model the IRQs as: >> >> PMIC >> | >> -------------------------------------------------- >> | | | | | >> IRQ1 IRQ2 IRQ3 I2C-IRQ CLIENT-IRQ >> >> Which is not the same really. I guess it is better then what we >> have though ? > > Hmm... There should not be difference in the hierarchy. add_linear == > create_linear. The propagation of *device* (not an IRQ) fwnode is just > convenient way to have IRQ domain be named (instead of 'unknown-N' or so). > Maybe I have read __irq_domain_add() code wrongly. Sorry, this is probably my bad. The first ASCII-art which I posted is how things actually work in HW. The second one is how I assumed that things would look like in some nested representation of the IRQ-domains given that all the IRQs mentioned in the ASCII-art now use the same fwnode as parent for their domain. But poking around in sysfs I don't see any hierarchical representation of the domains at all. Actually I cannot find any representation of the IRQ domains inside sysfs (I've never looked at / into this before) ? If what you say is right and the fwnode is only used to set a name (where can I see those names ?) then your patch is probably correct. > Nevertheless, thinking more about it, why we don't add an IRQ chip via regmap > IRQ API? There already is a regmap IRQ chip associated with the MFD device and the IRQ handling required here is somewhat tricky (see the comments in the driver) so I would prefer to keep this as is. >> Note I can test any changes made here, but I'm not 100% convinced that >> the current version of this patch is correct. > > If we settle on the idea first. I'm (slowly) looking forward to check another > CherryTrail device we have at the lab, but we lack of some (power) equipment > right now to setup it properly. I hope it may have the Whiskey Cove PMIC there. More testing is always welcome :) With that said, testing these changes really is not a lot of work for me. Regards, Hans