Re: [PATCH v2 5/6] esp_scsi: De-duplicate PIO routines

[Hannes Reinecke]

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@xxxxxxxxx>
> > > Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
> > > Tested-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
> > > ---
> > > 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
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