linux-kernel - Re: [PATCH] dmaengine: ti: k3-udma-glue: fix channel enable functions

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Date:   Wed, 16 Sep 2020 11:37:21 +0300
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Peter Ujfalusi <peter.ujfalusi@...com>,
        Vinod Koul <vkoul@...nel.org>, <dmaengine@...r.kernel.org>
CC:     Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>,
        Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH] dmaengine: ti: k3-udma-glue: fix channel enable functions



On 16/09/2020 11:35, Peter Ujfalusi wrote:
> 
> 
> On 15/09/2020 19.41, Grygorii Strashko wrote:
>> Now the K3 UDMA glue layer enable functions perform RMW operation on UDMA
>> RX/TX RT_CTL registers to set EN bit and enable channel, which is
>> incorrect, because only EN bit has to be set in those registers to enable
>> channel (all other bits should be cleared 0).
>> More over, this causes issues when bootloader leaves UDMA channel RX/TX
>> RT_CTL registers in incorrect state - TDOWN bit set, for example. As
>> result, UDMA channel will just perform teardown right after it's enabled.
>>
>> Hence, fix it by writing correct values (EN=1) directly in UDMA channel
>> RX/TX RT_CTL registers in k3_udma_glue_enable_tx/rx_chn() functions.
> 
> This is how the DMAengine driver deals with the enable.
> 
> Acked-by: Peter Ujfalusi <peter.ujfalusi@...com>

Sorry, but I'd need to resend v2 - based on wrong tree.
Worked too late yesterday :(

> 
>> Fixes: d70241913413 ("dmaengine: ti: k3-udma: Add glue layer for non DMAengine users")
>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>> ---
>>   drivers/dma/ti/k3-udma-glue.c | 15 +++------------
>>   1 file changed, 3 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/dma/ti/k3-udma-glue.c b/drivers/dma/ti/k3-udma-glue.c
>> index dc03880f021a..37d706cf3ba9 100644
>> --- a/drivers/dma/ti/k3-udma-glue.c
>> +++ b/drivers/dma/ti/k3-udma-glue.c
>> @@ -370,7 +370,6 @@ EXPORT_SYMBOL_GPL(k3_udma_glue_pop_tx_chn);
>>   
>>   int k3_udma_glue_enable_tx_chn(struct k3_udma_glue_tx_channel *tx_chn)
>>   {
>> -	u32 txrt_ctl;
>>   	int ret;
>>   
>>   	ret = xudma_navss_psil_pair(tx_chn->common.udmax,
>> @@ -383,15 +382,11 @@ int k3_udma_glue_enable_tx_chn(struct k3_udma_glue_tx_channel *tx_chn)
>>   
>>   	tx_chn->psil_paired = true;
>>   
>> -	txrt_ctl = UDMA_PEER_RT_EN_ENABLE;
>>   	xudma_tchanrt_write(tx_chn->udma_tchanx, UDMA_CHAN_RT_PEER_RT_EN_REG,
>> -			    txrt_ctl);
>> +			    UDMA_PEER_RT_EN_ENABLE);
>>   
>> -	txrt_ctl = xudma_tchanrt_read(tx_chn->udma_tchanx,
>> -				      UDMA_CHAN_RT_CTL_REG);
>> -	txrt_ctl |= UDMA_CHAN_RT_CTL_EN;
>>   	xudma_tchanrt_write(tx_chn->udma_tchanx, UDMA_CHAN_RT_CTL_REG,
>> -			    txrt_ctl);
>> +			    UDMA_CHAN_RT_CTL_EN);
>>   
>>   	k3_udma_glue_dump_tx_rt_chn(tx_chn, "txchn en");
>>   	return 0;
>> @@ -1059,7 +1054,6 @@ EXPORT_SYMBOL_GPL(k3_udma_glue_rx_flow_disable);
>>   
>>   int k3_udma_glue_enable_rx_chn(struct k3_udma_glue_rx_channel *rx_chn)
>>   {
>> -	u32 rxrt_ctl;
>>   	int ret;
>>   
>>   	if (rx_chn->remote)
>> @@ -1078,11 +1072,8 @@ int k3_udma_glue_enable_rx_chn(struct k3_udma_glue_rx_channel *rx_chn)
>>   
>>   	rx_chn->psil_paired = true;
>>   
>> -	rxrt_ctl = xudma_rchanrt_read(rx_chn->udma_rchanx,
>> -				      UDMA_CHAN_RT_CTL_REG);
>> -	rxrt_ctl |= UDMA_CHAN_RT_CTL_EN;
>>   	xudma_rchanrt_write(rx_chn->udma_rchanx, UDMA_CHAN_RT_CTL_REG,
>> -			    rxrt_ctl);
>> +			    UDMA_CHAN_RT_CTL_EN);
>>   
>>   	xudma_rchanrt_write(rx_chn->udma_rchanx, UDMA_CHAN_RT_PEER_RT_EN_REG,
>>   			    UDMA_PEER_RT_EN_ENABLE);
>>
> 
> - Péter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> 

-- 
Best regards,
grygorii