linux-kernel - Re: [PATCH v3 14/16] mmc: tmio: move TMIO_MASK_{READOP,WRITEOP} handling to correct place

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Date:   Sun, 4 Mar 2018 23:34:51 +0100
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-mmc@...r.kernel.org,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Ulf Magnusson <ulfalizer@...il.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Simon Horman <horms+renesas@...ge.net.au>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v3 14/16] mmc: tmio: move TMIO_MASK_{READOP,WRITEOP}
 handling to correct place

On Thu, Jan 18, 2018 at 01:28:14AM +0900, Masahiro Yamada wrote:
> As far as I tested the IP on UniPhier SoCs, TMIO_STAT_{RXRDY,TXRQ}
> are asserted for DMA mode as well as for PIO.  I need to disable the
> those IRQs in dma_ops->start hook, otherwise the DMA transfer fails
> with the following error message:
>   PIO IRQ in DMA mode!
> 
> Renesas chips are the same cases since I see their dma_ops->start
> hooks explicitly clear TMIO_STAT_{RXRDY,TXRQ} (with nice comment!).
> 
> If we do this sanity check in TMIO MMC core, RXRDY/TXRQ handling
> should be entirely moved to the core.  tmio_mmc_cmd_irq() will
> be a suitable place to disable them.
> 
> The probe function sets TMIO_MASK_{READOP,WRITEOP} but this is odd.
> 
>     /* Unmask the IRQs we want to know about */
>     if (!_host->chan_rx)
>             irq_mask |= TMIO_MASK_READOP;
>     if (!_host->chan_tx)
>             irq_mask |= TMIO_MASK_WRITEOP;
> 
> At this point, _host->{chan_rx,chan_tx} are _always_ NULL because
> tmio_mmc_request_dma() is called after this code.  Consequently,
> TMIO_MASK_{READOP,WRITEOP} are set here whether DMA is used or not.
> Remove this pointless code.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Reviewed-by: Wolfram Sang <wsa+renesas@...g-engineering.com>


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