linux-kernel - Re: [PATCH RFT] usb: dwc2: gadget: Fix fifo size configuration

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Date:   Tue, 20 Dec 2016 15:49:27 +0000
From:   Sevak Arakelyan <SEVAK.ARAKELYAN@...opsys.com>
To:     Stefan Wahren <stefan.wahren@...e.com>,
        John Youn <John.Youn@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     Michael Niewoehner <linux@...ewoehner.de>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Razmik Karapetyan <Razmik.Karapetyan@...opsys.com>,
        Dinh Nguyen <dinguyen@...nsource.altera.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Heiko Stuebner <heiko@...ech.de>,
        "Vardan Mikayelyan" <Vardan.Mikayelyan@...opsys.com>
Subject: Re: [PATCH RFT] usb: dwc2: gadget: Fix fifo size configuration

On 12/20/2016 6:20 PM, Stefan Wahren wrote:
> Hi Sevak,
>
>> Sevak Arakelyan <SEVAK.ARAKELYAN@...opsys.com> hat am 20. Dezember 2016 um 13:57 geschrieben:
>>
>>
>> On 12/19/2016 8:39 PM, Stefan Wahren wrote:
>>> Currently the upper limit for the endpoint index during fifo size
>>> config was always 16 instead of the available endpoints. So fix this
>>> by using the determined amount of endpoints and avoid a warning about
>>> "insufficient fifo memory" on bcm2835 which has only 8 endpoints.
>>>
>>> Signed-off-by: Stefan Wahren <stefan.wahren@...e.com>
>>> Fixes: 0a176279db68 ("usb: dwc2: gadget: configure fifos from device tree")
>>> ---
>>>  drivers/usb/dwc2/gadget.c |    2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> Since revert of ("usb: dwc2: gadget: fix TX FIFO size and address") which
>>> caused regressions on some platforms this is the second attempt to fix
>>> gadget support for bcm2835.
>>>
>>> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
>>> index b95930f..b00184c 100644
>>> --- a/drivers/usb/dwc2/gadget.c
>>> +++ b/drivers/usb/dwc2/gadget.c
>>> @@ -228,7 +228,7 @@ static void dwc2_hsotg_init_fifo(struct dwc2_hsotg *hsotg)
>>>  	 * them to endpoints dynamically according to maxpacket size value of
>>>  	 * given endpoint.
>>>  	 */
>>> -	for (ep = 1; ep < MAX_EPS_CHANNELS; ep++) {
>>> +	for (ep = 1; ep < hsotg->num_of_eps; ep++) {
>>>  		if (!txfsz[ep])
>>>  			continue;
>>>  		val = addr;
>> Hi Stefan,
>>
>>     This patch is only temporary, not full solution for bcm2835 and in
>> the loop you need to use hsotg->num_of_eps in shared FIFO mode and the
>> number of device IN EPs which is in GHWCFG4 with mask
>> GHWCFG4_NUM_IN_EPS_MASK in dedicated FIFO mode.
> i don't have any documentation for this. So i tried to fix this obviously error.
>
>>     The upper limit is up to 15 but the actual number of FIFOa are being
>> configured according to the given legacy array
>> DWC2_G_P_LEGACY_TX_FIFO_SIZE {256, 256, 256, 256, 768, 768, 768, 768, 0,
>> 0, 0, 0, 0, 0, 0}, in that case it is 8 FIFOs. The legacy values are the
>> main issue. We must do correct calculation according to FIFO operation
>> mode, device operation mode, take into consideration the EP Info Block
>> which must be at the end of total FIFO and after that configure correct
>> number of FIFOs with correct size of depth on every setup. We prepared a
>> patch series to fix that issue and it is under internal review and
>> testing process and will be submitted soon.
> I wanted to avoid this by providing the TX FIFO sizes via DT [1].
>
> Sorry for my impatience.
>
> [1] - https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_lategoodbye_rpi-2Dzero_commit_a6ec75dd8ea6a7ce0609ae082d3fa748beaba22c&d=DgICaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=SniH1MMI5_rJOm61HpL5IYZquCv0UB108rKN0g5Qj8Q&m=ENp09nlehChUcfWd9a_imoGZ2oImaklDC0eqqLbhXIs&s=-Sn2hwPd6iMDrb8hFHDiXURw62nYhMi5CY4oW8h1w94&e= 
>
>>   
>> Thanks,
>> Sevak
>>
The upper described flow is only for setting default FIFO depths instead
of legacy values. It is dividing available total FIFO depth between TX
FIFOs, but if you want to give your own depths you can give them via DT,
updated flow only will do validation of given DT values and will set to
default ones only if the given ones are getting out of FIFO bounds. So
you can give your calculated TX FIFO sizes via DT if our patch series
will not fix the existing issue on bcm2835.