linux-kernel - Re: [PATCH] wireless: introduce POWEROF2_BLOCKSIZE

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Date:	Fri, 6 Feb 2009 15:47:38 +0800
From:	Bryan Wu <cooloney@...nel.org>
To:	Dan Williams <dcbw@...hat.com>
Cc:	linville@...driver.com, linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org, Cliff Cai <cliff.cai@...log.com>
Subject: Re: [PATCH] wireless: introduce POWEROF2_BLOCKSIZE_ONLY option

On Thu, Feb 5, 2009 at 11:03 PM, Dan Williams <dcbw@...hat.com> wrote:
> On Thu, 2009-02-05 at 15:30 +0800, Bryan Wu wrote:
>> From: Cliff Cai <cliff.cai@...log.com>
>>
>> Introduce POWEROF2_BLOCKSIZE_ONLY option for those SD/SDIO host
>> which only support transferring block with size of power-of-2
>
> Is the point here to avoid copying in the controller code?  As with the
> other patches on libertas-dev, I really dislike adding code to *every
> SDIO driver* just because the host has certain restrictions.  I'd much
> rather that the host/controller code became aware of it's own
> restrictions, and exposed those generically to drivers above it.
> Without a KConfig option.
>
> Seriously.  The host knows what it needs.  The code to handle that
> should go in the host.
>

I agree here.

> How about adding a method like "sdio_align_size" that takes the
> controller's constraints into account?  That seems a lot cleaner than
> adding #define/KConfig junk to every SDIO driver in the kernel.  One
> less codepath to test, makes your life and all our lives easier.
>

So we plan to add method ".sdio_align_size" to SDIO stack.
And Blackfin host driver will implement this method while others will
implement this as a dummy function.

In libertas, we need to call this method to take this constraints into account.

Thanks
-Bryan


>> [ Bryan Wu <cooloney@...nel.org>:
>>  - remove some useless coding style cleanup
>>  - using roundup() function as upstream does
>> ]
>>
>> Signed-off-by: Cliff Cai <cliff.cai@...log.com>
>> Signed-off-by: Bryan Wu <cooloney@...nel.org>
>> ---
>>  drivers/net/wireless/Kconfig            |    6 ++++++
>>  drivers/net/wireless/libertas/if_sdio.c |   16 ++++++++++++++++
>>  2 files changed, 22 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/net/wireless/Kconfig b/drivers/net/wireless/Kconfig
>> index e4f9f74..a2685fa 100644
>> --- a/drivers/net/wireless/Kconfig
>> +++ b/drivers/net/wireless/Kconfig
>> @@ -151,6 +151,12 @@ config LIBERTAS_SDIO
>>       ---help---
>>         A driver for Marvell Libertas 8385 and 8686 SDIO devices.
>>
>> +config POWEROF2_BLOCKSIZE_ONLY
>> +     bool "Support transferring block with size of power-of-2 only"
>> +     depends on LIBERTAS_SDIO
>> +     ---help---
>> +       For SD/SDIO host which only supports transferring block with size of power-of-2.
>> +
>>  config LIBERTAS_DEBUG
>>       bool "Enable full debugging output in the Libertas module."
>>       depends on LIBERTAS
>> diff --git a/drivers/net/wireless/libertas/if_sdio.c b/drivers/net/wireless/libertas/if_sdio.c
>> index 4519d73..5efc056 100644
>> --- a/drivers/net/wireless/libertas/if_sdio.c
>> +++ b/drivers/net/wireless/libertas/if_sdio.c
>> @@ -272,6 +272,11 @@ static int if_sdio_card_to_host(struct if_sdio_card *card)
>>        */
>>       chunk = sdio_align_size(card->func, size);
>>
>> +/* For SD/SDIO host which only supports transferring block with size of power-of-2 */
>> +#if defined(CONFIG_POWEROF2_BLOCKSIZE_ONLY)
>> +     chunk = (chunk + card->func->cur_blksize - 1) /
>> +                     card->func->cur_blksize * card->func->cur_blksize;
>> +#endif
>>       ret = sdio_readsb(card->func, card->buffer, card->ioport, chunk);
>>       if (ret)
>>               goto out;
>> @@ -581,8 +586,14 @@ static int if_sdio_prog_real(struct if_sdio_card *card)
>>                       lbs_deb_sdio("sending %d bytes (%d bytes) chunk\n",
>>                               chunk_size, (chunk_size + 31) / 32 * 32);
>>  */
>> +/* For SD/SDIO host which only supports transferring block with size of power-of-2 */
>> +#if defined(CONFIG_POWEROF2_BLOCKSIZE_ONLY)
>> +                     ret = sdio_writesb(card->func, card->ioport,
>> +                             chunk_buffer, roundup(chunk_size, 256);
>> +#else
>>                       ret = sdio_writesb(card->func, card->ioport,
>>                               chunk_buffer, roundup(chunk_size, 32));
>> +#endif
>>                       if (ret)
>>                               goto release;
>>
>> @@ -699,6 +710,11 @@ static int if_sdio_host_to_card(struct lbs_private *priv,
>>        */
>>       size = sdio_align_size(card->func, nb + 4);
>>
>> +/* For SD/SDIO host which only supports transferring block with size of power-of-2 */
>> +#if defined(CONFIG_POWEROF2_BLOCKSIZE_ONLY)
>> +     size = (size + card->func->cur_blksize - 1) /
>> +                     card->func->cur_blksize * card->func->cur_blksize;
>> +#endif
>>       packet = kzalloc(sizeof(struct if_sdio_packet) + size,
>>                       GFP_ATOMIC);
>>       if (!packet) {
>
>
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