Messages in this thread | | | Subject | Re: [PATCH v6 2/4] leds: Add driver for Qualcomm LPG | From | Marijn Suijten <> | Date | Thu, 29 Apr 2021 21:31:01 +0200 |
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On 4/29/21 12:39 AM, Bjorn Andersson wrote: > On Sun 18 Apr 16:54 CDT 2021, Marijn Suijten wrote: > >> Hi Bjorn, >> >> On 10/21/20 10:12 PM, Bjorn Andersson wrote: >>> The Light Pulse Generator (LPG) is a PWM-block found in a wide range of >>> PMICs from Qualcomm. It can operate on fixed parameters or based on a >>> lookup-table, altering the duty cycle over time - which provides the >>> means for e.g. hardware assisted transitions of LED brightness. >>> >>> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> >>> Tested-by: Luca Weiss <luca@z3ntu.xyz> >> >> >> Thanks for these patches. I have tested them successfully on the Sony >> Xperia XA2 (Discovery, Nile platform) with the leds on the PM660l - feel >> free to add my Tested-by. Should I send the configuration your way for >> inclusion in this patch, or submit them separately (either applied after, or >> included as separate patches in the next version of this series)? >> > > Thanks for testing, let's try to land this first iteration first and > then we can add PM660l and PM8150* definitions/support on top.
I'll keep an eye out for when these patches land and send them on top. Feel free to add me to the CC list for future revisions.
>>> +/** >>> + * struct lpg_data - initialization data >>> + * @lut_base: base address of LUT block >>> + * @lut_size: number of entries in LUT >>> + * @triled_base: base address of TRILED >>> + * @pwm_9bit_mask: bitmask for switching from 6bit to 9bit pwm >> >> >> Our downstream kernel derives this from the "LPG subtype" for each distinct >> channel, read from register offset +0x5. A value of 0xb is subtype "PWM" >> with a shift of 2, a value of 0x11 is subtype "LPG_LITE" with a shift of 4. >> Can we do the same here instead of hardcoding it for all channels in the LPG >> at once? How should we determine if the mask is one or two bits wide, for >> the 3<<4 case? >> > > I don't see any obvious solution to the latter, so perhaps we should > just stick with defining this per compatible? Or am I reading your > suggestion wrong?
Assuming these devices have a different "LPG subtype" you should be able to read their value and add it to the list as third option. Alternatively, can you point out the driver this `3<<4` mask was based on? With all the information available it should be possible to derive this from hardware for every channel instead of hardcoding it.
>>> + >>> + bitmap_clear(lpg->lut_bitmap, 0, lpg->lut_size); >>> + return lpg->lut_bitmap ? 0 : -ENOMEM; >>> +} >>> + >>> +static int lpg_probe(struct platform_device *pdev) >>> +{ >>> + struct device_node *np; >>> + struct lpg *lpg; >>> + int ret; >>> + int i; >>> + >>> + lpg = devm_kzalloc(&pdev->dev, sizeof(*lpg), GFP_KERNEL); >>> + if (!lpg) >>> + return -ENOMEM; >>> + >>> + lpg->data = of_device_get_match_data(&pdev->dev); >>> + if (!lpg->data) >>> + return -EINVAL; >>> + >>> + lpg->dev = &pdev->dev; >>> + >>> + lpg->map = dev_get_regmap(pdev->dev.parent, NULL); >>> + if (!lpg->map) { >>> + dev_err(&pdev->dev, "parent regmap unavailable\n"); >>> + return -ENXIO; >>> + } >>> + >>> + ret = lpg_init_channels(lpg); >>> + if (ret < 0) >>> + return ret; >>> + >>> + ret = lpg_init_triled(lpg); >>> + if (ret < 0) >>> + return ret; >>> + >>> + ret = lpg_init_lut(lpg); >>> + if (ret < 0) >>> + return ret; >> >> >> How about turning these returns into dev_err_probe? I'm not sure if that's >> the expected way to go nowadays, but having some form of logging when a >> driver fails to probe is always good to have. >> > > The intention is that each code path through these functions will either > pass or spit out an error in the log. I looked through them again and > think I cover all paths...
That is true, all the errors not covered are extremely unlikely like -ENOMEM. I vaguely recall having to insert extra logging to get through initial probe, but that might have been something inside lpg_add_led as well. Fine to leave this as it is.
- Marijn
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