linux-kernel - Re: [PATCH v3] mfd:rtsx: do retry when dma transfer error

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Message-ID: <20170407111316.fcjhydgbnf2yulaw@dell>
Date:   Fri, 7 Apr 2017 12:13:16 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     冯伟linux <steven_feng@...lsil.com.cn>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] mfd:rtsx: do retry when dma transfer error

On Fri, 07 Apr 2017, 冯伟linux wrote:

> HI lee.jones
> 
>     I submitted my  patch a few months ago, but the patch was not merged.
> I want to know what causes this, so that I can update the patch and make
> the patch merged.

The patch was missed.  I do not know why.

> steven feng
> Realsil Microelectronics CO. LTD.
> Mobile：181-6899-0403  Ext：57594
> 
> On 2017年01月05日 17:01, 冯伟linux wrote:
> > From: steven_feng <steven_feng@...lsil.com.cn>

Should be "Steven Feng"

> > the request should be reissued when dma transfer error.
> > for rts5227, the clock freq need to step reduce when error occurred.

Please use correct grammar, including full-stops and capital letters.

> > Signed-off-by: steven_feng <steven_feng@...lsil.com.cn>

"Steven Feng"

> > ---
> >  drivers/mfd/rtsx_pcr.c       | 17 +++++++++++++++--
> >  include/linux/mfd/rtsx_pci.h |  5 +++++
> >  2 files changed, 20 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mfd/rtsx_pcr.c b/drivers/mfd/rtsx_pcr.c
> > index 98029ee..3161c46 100644
> > --- a/drivers/mfd/rtsx_pcr.c
> > +++ b/drivers/mfd/rtsx_pcr.c
> > @@ -30,6 +30,7 @@
> >  #include <linux/platform_device.h>
> >  #include <linux/mfd/core.h>
> >  #include <linux/mfd/rtsx_pci.h>
> > +#include <linux/mmc/card.h>

Why is this required?

> >  #include <asm/unaligned.h>
> >  
> >  #include "rtsx_pcr.h"
> > @@ -452,8 +453,12 @@ int rtsx_pci_dma_transfer(struct rtsx_pcr *pcr, struct scatterlist *sglist,
> >  	}
> >  
> >  	spin_lock_irqsave(&pcr->lock, flags);
> > -	if (pcr->trans_result == TRANS_RESULT_FAIL)
> > -		err = -EINVAL;
> > +	if (pcr->trans_result == TRANS_RESULT_FAIL) {
> > +		err = -EILSEQ;

"Illegal byte sequence", really?

> > +		if (pcr->dma_error_count < RTS_MAX_TIMES_FREQ_REDUCTION)
> > +			pcr->dma_error_count++;
> > +	}
> > +
> >  	else if (pcr->trans_result == TRANS_NO_DEVICE)
> >  		err = -ENODEV;
> >  	spin_unlock_irqrestore(&pcr->lock, flags);
> > @@ -659,6 +664,13 @@ int rtsx_pci_switch_clock(struct rtsx_pcr *pcr, unsigned int card_clock,
> >  	if (err < 0)
> >  		return err;
> >  
> > +	/* Each time dma transfer error occurs, card clock decreased by 20MHz */

s/dma/DMA/

I would reword as follows:

"Reduce MMC card clock by 20MHz each time a DMA transfer error occurs"

> > +	if (card_clock == UHS_SDR104_MAX_DTR &&
> > +		pcr->dma_error_count &&
> > +		PCI_PID(pcr) == RTS5227_DEVICE_ID)
> > +		card_clock = (UHS_SDR104_MAX_DTR -
> > +			pcr->dma_error_count * 20000000);

... but won't this only reduce the clock frequency just once?

There is no point bracketing the whole statement.

But you do need to bracket one (the second) section of it.

> >  	card_clock /= 1000000;
> >  	pcr_dbg(pcr, "Switch card clock to %dMHz\n", card_clock);
> >  
> > @@ -894,6 +906,7 @@ static irqreturn_t rtsx_pci_isr(int irq, void *dev_id)
> >  			pcr->card_removed |= SD_EXIST;
> >  			pcr->card_inserted &= ~SD_EXIST;
> >  		}
> > +		pcr->dma_error_count = 0;
> >  	}
> >  
> >  	if (int_reg & MS_INT) {
> > diff --git a/include/linux/mfd/rtsx_pci.h b/include/linux/mfd/rtsx_pci.h
> > index 7eb7cba..116816f 100644
> > --- a/include/linux/mfd/rtsx_pci.h
> > +++ b/include/linux/mfd/rtsx_pci.h
> > @@ -850,6 +850,9 @@
> >  
> >  #define rtsx_pci_init_cmd(pcr)		((pcr)->ci = 0)
> >  
> > +#define RTS5227_DEVICE_ID		0x5227
> > +#define RTS_MAX_TIMES_FREQ_REDUCTION	8
> > +
> >  struct rtsx_pcr;
> >  
> >  struct pcr_handle {
> > @@ -957,6 +960,8 @@ struct rtsx_pcr {
> >  
> >  	int				num_slots;
> >  	struct rtsx_slot		*slots;
> > +
> > +	u8				dma_error_count;
> >  };
> >  
> >  #define CHK_PCI_PID(pcr, pid)		((pcr)->pci->device == (pid))
> 

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-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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