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SubjectRe: [PATCH v2 5/6] esp_scsi: De-duplicate PIO routines
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On 10/15/18 8:25 AM, Finn Thain wrote:
> On Mon, 15 Oct 2018, Hannes Reinecke wrote:
>
>> On 10/14/18 8:12 AM, Finn Thain wrote:
>>> As a temporary measure, the code to implement PIO transfers was
>>> duplicated in zorro_esp and mac_esp. Now that it has stabilized
>>> move the common code into the core driver but don't build it unless
>>> needed.
>>>
>>> This replaces the inline assembler with more portable writesb() calls.
>>> Optimizing the m68k writesb() implementation is a separate patch.
>>>
>>> Tested-by: Stan Johnson <userm57@yahoo.com>
>>> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
>>> Tested-by: Michael Schmitz <schmitzmic@gmail.com>
>>> ---
>>> Changed since v1:
>>> - Use shost_printk() instead of pr_err().
>>> - Add new symbol CONFIG_SCSI_ESP_PIO to Kconfig.
>>> ---
>>> drivers/scsi/Kconfig | 6 +
>>> drivers/scsi/esp_scsi.c | 128 +++++++++++++++++++++
>>> drivers/scsi/esp_scsi.h | 5 +
>>> drivers/scsi/mac_esp.c | 173 +----------------------------
>>> drivers/scsi/zorro_esp.c | 232 ++++++---------------------------------
>>> 5 files changed, 179 insertions(+), 365 deletions(-)
>>>
[ .. ]
>>> diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
>>> index d0c032803749..2590e5eda595 100644
>>> --- a/drivers/scsi/esp_scsi.h
>>> +++ b/drivers/scsi/esp_scsi.h
>>> @@ -431,6 +431,7 @@ struct esp_driver_ops {
>>> struct esp {
>>> void __iomem *regs;
>>> void __iomem *dma_regs;
>>> + u8 __iomem *fifo_reg;
>>> const struct esp_driver_ops *ops;
>>> @@ -540,6 +541,7 @@ struct esp {
>>> void *dma;
>>> int dmarev;
>>> + int send_cmd_error;
>>> int send_cmd_residual;
>>> };
>>>
>> These variables are only used within esp_send_pio_cmd(); consider making them
>> conditional based on the config option.
>>
>
> In the case of send_cmd_residual, that would mean a second #ifdef added to
> esp_data_bytes_sent() where it gets used. I'm happy to comply but I fear
> that all these #ifdefs may harm readability...
>
> There are already other variables in struct esp that may go unused, such
> as dma_regs, that don't have #ifdefs to elide them. Are these also
> problematic in some way?
>
The unused fields in the struct are not so much an issue; in fact, it
rather complicated things when having individual fields in the struct
surrounded by CONFIG_XXX, as then the order of the fields would change
depending on the configuration. Which makes it really hard to debug ..

However, the function declaration really is a worry, as the actual
function body only exists when the config option is enabled.
So either add a dummy function or surround the function declaration by
CONFIG_ESP_PIO.
Otherwise I think Dan Carpenter and the likes are guaranteed to send you
a nice mail complaining about this ...

Cheers,

Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

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